diff --git a/x-pack/plugins/observability_solution/synthetics/common/runtime_types/monitor_management/monitor_types.ts b/x-pack/plugins/observability_solution/synthetics/common/runtime_types/monitor_management/monitor_types.ts
index 578d823aafae2..9e38a3d7b9182 100644
--- a/x-pack/plugins/observability_solution/synthetics/common/runtime_types/monitor_management/monitor_types.ts
+++ b/x-pack/plugins/observability_solution/synthetics/common/runtime_types/monitor_management/monitor_types.ts
@@ -259,6 +259,8 @@ export const BrowserSensitiveSimpleFieldsCodec = t.intersection([
   CommonFieldsCodec,
 ]);
 
+export type BrowserSensitiveSimpleFields = t.TypeOf<typeof BrowserSensitiveSimpleFieldsCodec>;
+
 export const ThrottlingConfigValueCodec = t.interface({
   download: t.string,
   upload: t.string,
diff --git a/x-pack/plugins/observability_solution/synthetics/server/common/inline_to_zip.test.ts b/x-pack/plugins/observability_solution/synthetics/server/common/inline_to_zip.test.ts
new file mode 100644
index 0000000000000..9f02f129ea077
--- /dev/null
+++ b/x-pack/plugins/observability_solution/synthetics/server/common/inline_to_zip.test.ts
@@ -0,0 +1,31 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { inlineToProjectZip } from './inline_to_zip';
+import { unzipFile } from './unzip_project_code';
+
+describe('inlineToProjectZip', () => {
+  it('should return base64 encoded zip data', async () => {
+    const inlineJourney = `
+step('goto', () => page.goto('https://elastic.co'));
+step('throw error', () => { throw new Error('error'); });
+`;
+    const result = await inlineToProjectZip(inlineJourney, 'testMonitorId', jest.fn() as any);
+
+    expect(result.length).toBeGreaterThan(0);
+    expect(await unzipFile(result)).toEqual(
+      `import { journey, step, expect, mfa } from '@elastic/synthetics';
+
+journey('inline', ({ page, context, browser, params, request }) => {
+
+step('goto', () => page.goto('https://elastic.co'));
+step('throw error', () => { throw new Error('error'); });
+
+});`
+    );
+  });
+});
diff --git a/x-pack/plugins/observability_solution/synthetics/server/common/inline_to_zip.ts b/x-pack/plugins/observability_solution/synthetics/server/common/inline_to_zip.ts
new file mode 100644
index 0000000000000..56825776b7c93
--- /dev/null
+++ b/x-pack/plugins/observability_solution/synthetics/server/common/inline_to_zip.ts
@@ -0,0 +1,47 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { Logger } from '@kbn/logging';
+import archiver from 'archiver';
+import { MemWritable } from './mem_writable';
+
+function wrapInlineInProject(inlineJourney: string) {
+  return `import { journey, step, expect, mfa } from '@elastic/synthetics';
+
+journey('inline', ({ page, context, browser, params, request }) => {
+${inlineJourney}
+});`;
+}
+
+export async function inlineToProjectZip(
+  inlineJourney: string,
+  monitorId: string,
+  logger: Logger
+): Promise<string> {
+  const mWriter = new MemWritable();
+  try {
+    await new Promise<void>((resolve, reject) => {
+      const archive = archiver('zip', {
+        zlib: { level: 9 },
+      });
+      archive.on('error', reject);
+      mWriter.on('close', resolve);
+      archive.pipe(mWriter);
+      archive.append(wrapInlineInProject(inlineJourney), {
+        name: 'inline.journey.ts',
+        // Date is fixed to Unix epoch so the file metadata is
+        // not modified everytime when files are bundled
+        date: new Date('1970-01-01'),
+      });
+      return archive.finalize();
+    });
+  } catch (e) {
+    logger.error(`Failed to create zip for inline monitor ${monitorId}`);
+    throw e;
+  }
+  return mWriter.buffer.toString('base64');
+}
diff --git a/x-pack/plugins/observability_solution/synthetics/server/common/mem_writable.test.ts b/x-pack/plugins/observability_solution/synthetics/server/common/mem_writable.test.ts
new file mode 100644
index 0000000000000..fac4f3834dafa
--- /dev/null
+++ b/x-pack/plugins/observability_solution/synthetics/server/common/mem_writable.test.ts
@@ -0,0 +1,37 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { MemWritable } from './mem_writable';
+
+describe('MemWritable', () => {
+  it('should write chunks to the buffer', async () => {
+    const memWritable = new MemWritable();
+
+    const chunk1 = `step('goto', () => page.goto('https://elastic.co'));`;
+    const chunk2 = `step('throw error', () => { throw new Error('error'); });`;
+    const expectedBuffer = Buffer.from(chunk1 + chunk2);
+
+    await new Promise<void>((resolve, reject) => {
+      memWritable.write(Buffer.from(chunk1), (err) => {
+        if (err) {
+          reject(err);
+        }
+        expect(memWritable.buffer).toEqual(Buffer.from(chunk1));
+        resolve();
+      });
+    });
+    await new Promise<void>((resolve, reject) => {
+      memWritable.write(Buffer.from(chunk2), (err) => {
+        if (err) {
+          reject(err);
+        }
+        resolve();
+      });
+    });
+    expect(memWritable.buffer).toEqual(expectedBuffer);
+  });
+});
diff --git a/x-pack/plugins/observability_solution/synthetics/server/common/mem_writable.ts b/x-pack/plugins/observability_solution/synthetics/server/common/mem_writable.ts
new file mode 100644
index 0000000000000..3e1091b77ac4a
--- /dev/null
+++ b/x-pack/plugins/observability_solution/synthetics/server/common/mem_writable.ts
@@ -0,0 +1,29 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { Writable, WritableOptions } from 'node:stream';
+
+export class MemWritable extends Writable {
+  private _queue: Buffer[];
+  constructor(opts?: WritableOptions) {
+    super(opts);
+    this._queue = [];
+  }
+
+  public get buffer(): Buffer {
+    return Buffer.concat(this._queue);
+  }
+
+  _write(
+    chunk: Buffer,
+    _encoding: BufferEncoding,
+    callback: (error?: Error | null | undefined) => void
+  ): void {
+    this._queue.push(chunk);
+    callback();
+  }
+}
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor.test.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor.test.ts
new file mode 100644
index 0000000000000..1e9db8b183201
--- /dev/null
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor.test.ts
@@ -0,0 +1,143 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { ConfigKey, SyntheticsMonitor } from '../../../common/runtime_types';
+import { UpsertMonitorAPI } from './add_monitor/upsert_monitor_api';
+
+describe('hydrateMonitorFields', () => {
+  it('does not add project field value for inline browser monitor', () => {
+    const normalizedMonitor: SyntheticsMonitor = {
+      // @ts-expect-error extra field
+      type: 'browser',
+      // @ts-expect-error extra field
+      form_monitor_type: 'multistep',
+      enabled: true,
+      alert: { status: { enabled: true }, tls: { enabled: true } },
+      // @ts-expect-error extra field
+      schedule: { unit: 'm', number: '10' },
+      'service.name': '',
+      config_id: '',
+      tags: [],
+      timeout: null,
+      name: 'test-once-more',
+      locations: [{ id: 'dev', label: 'Dev Service', isServiceManaged: true }],
+      namespace: 'default',
+      // @ts-expect-error extra field
+      origin: 'ui',
+      journey_id: '',
+      hash: '',
+      id: '',
+      params: '',
+      max_attempts: 2,
+      project_id: '',
+      playwright_options: '',
+      __ui: { script_source: { is_generated_script: false, file_name: '' } },
+      'url.port': null,
+      'source.inline.script': `step('goto', () => page.goto('https://elastic.co'))
+step('fail', () => {
+  throw Error('fail');
+})`,
+      playwright_text_assertion: '',
+      urls: '',
+      screenshots: 'on',
+      synthetics_args: [],
+      'filter_journeys.match': '',
+      'filter_journeys.tags': [],
+      ignore_https_errors: false,
+      throttling: {
+        value: { download: '5', upload: '3', latency: '20' },
+        id: 'default',
+        label: 'Default',
+      },
+      'ssl.certificate_authorities': '',
+      'ssl.certificate': '',
+      'ssl.key': '',
+      'ssl.key_passphrase': '',
+      'ssl.verification_mode': 'full',
+      'ssl.supported_protocols': ['TLSv1.1', 'TLSv1.2', 'TLSv1.3'],
+    };
+
+    const api = new UpsertMonitorAPI({
+      request: {
+        query: {
+          preserve_namespace: true,
+        },
+      },
+      server: {
+        logger: jest.fn(),
+      },
+    } as any);
+    const hydratedMonitor = api.hydrateMonitorFields({
+      normalizedMonitor,
+      newMonitorId: 'testMonitorId',
+    });
+
+    expect((hydratedMonitor as any)[ConfigKey.SOURCE_PROJECT_CONTENT]).toBeUndefined();
+  });
+
+  it('does not add b64 zip data to lightweight monitors', () => {
+    const newMonitorId = 'testMonitorId';
+    const routeContext = {
+      request: {
+        query: {
+          preserve_namespace: true,
+        },
+      },
+      server: {
+        logger: jest.fn(),
+      },
+    };
+    const normalizedMonitor: SyntheticsMonitor = {
+      // @ts-expect-error extra field
+      type: 'tcp',
+      // @ts-expect-error extra field
+      form_monitor_type: 'tcp',
+      enabled: true,
+      alert: { status: { enabled: true }, tls: { enabled: true } },
+      // @ts-expect-error extra field
+      schedule: { number: '3', unit: 'm' },
+      'service.name': '',
+      config_id: '',
+      tags: [],
+      timeout: '16',
+      name: 'tcp://google.com:80',
+      locations: [{ id: 'dev', label: 'Dev Service', isServiceManaged: true }],
+      namespace: 'default',
+      // @ts-expect-error extra field
+      origin: 'ui',
+      journey_id: '',
+      hash: '',
+      id: '',
+      params: '',
+      max_attempts: 2,
+      __ui: { is_tls_enabled: false },
+      hosts: 'tcp://google.com:80',
+      urls: '',
+      'url.port': null,
+      proxy_url: '',
+      proxy_use_local_resolver: false,
+      'check.receive': '',
+      'check.send': '',
+      mode: 'any',
+      ipv4: true,
+      ipv6: true,
+      'ssl.certificate_authorities': '',
+      'ssl.certificate': '',
+      'ssl.key': '',
+      'ssl.key_passphrase': '',
+      'ssl.verification_mode': 'full',
+      'ssl.supported_protocols': ['TLSv1.1', 'TLSv1.2', 'TLSv1.3'],
+    };
+    const api = new UpsertMonitorAPI(routeContext as any);
+    const hydratedMonitor = api.hydrateMonitorFields({
+      normalizedMonitor,
+      newMonitorId,
+    });
+
+    expect((hydratedMonitor as any)[ConfigKey.SOURCE_PROJECT_CONTENT]).toBeFalsy();
+  });
+});
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor.ts
index f2c8f0974a6b4..2989bf1d8f36b 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor.ts
@@ -9,11 +9,12 @@ import { SavedObjectsErrorHelpers } from '@kbn/core/server';
 import { i18n } from '@kbn/i18n';
 import { validatePermissions } from './edit_monitor';
 import { InvalidLocationError } from '../../synthetics_service/project_monitor/normalizers/common_fields';
-import { AddEditMonitorAPI, CreateMonitorPayLoad } from './add_monitor/add_monitor_api';
+import { UpsertMonitorAPI, CreateMonitorPayLoad } from './add_monitor/upsert_monitor_api';
 import { SyntheticsRestApiRouteFactory } from '../types';
 import { SYNTHETICS_API_URLS } from '../../../common/constants';
 import { normalizeAPIConfig, validateMonitor } from './monitor_validation';
 import { mapSavedObjectToMonitor } from './formatters/saved_object_to_monitor';
+import { mapInlineToProjectFields } from '../../synthetics_service/utils/map_inline_to_project_fields';
 
 export const addSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () => ({
   method: 'POST',
@@ -39,7 +40,7 @@ export const addSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () => ({
     // usually id is auto generated, but this is useful for testing
     const { id, internal } = request.query;
 
-    const addMonitorAPI = new AddEditMonitorAPI(routeContext);
+    const addMonitorAPI = new UpsertMonitorAPI(routeContext);
 
     const {
       locations,
@@ -86,7 +87,15 @@ export const addSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () => ({
         });
       }
 
-      const normalizedMonitor = validationResult.decodedMonitor;
+      const normalizedMonitor = Object.assign(
+        {},
+        validationResult.decodedMonitor,
+        await mapInlineToProjectFields({
+          monitorType: validationResult.decodedMonitor?.type,
+          monitor: validationResult?.decodedMonitor,
+          logger: server.logger,
+        })
+      );
 
       const err = await validatePermissions(routeContext, normalizedMonitor.locations);
       if (err) {
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/add_monitor_api.test.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/upsert_monitor_api.test.ts
similarity index 98%
rename from x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/add_monitor_api.test.ts
rename to x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/upsert_monitor_api.test.ts
index 47429f7f037ef..497fd5c1cc1bc 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/add_monitor_api.test.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/upsert_monitor_api.test.ts
@@ -5,7 +5,7 @@
  * 2.0.
  */
 
-import { AddEditMonitorAPI } from './add_monitor_api';
+import { UpsertMonitorAPI } from './upsert_monitor_api';
 import { SyntheticsMonitorClient } from '../../../synthetics_service/synthetics_monitor/synthetics_monitor_client';
 import { SyntheticsService } from '../../../synthetics_service/synthetics_service';
 
@@ -16,7 +16,7 @@ describe('AddNewMonitorsPublicAPI', () => {
         enabled: true,
       },
     } as any);
-    const api = new AddEditMonitorAPI({
+    const api = new UpsertMonitorAPI({
       syntheticsMonitorClient: new SyntheticsMonitorClient(syntheticsService, {} as any),
       request: {
         body: {},
@@ -55,7 +55,7 @@ describe('AddNewMonitorsPublicAPI', () => {
     const syntheticsService = new SyntheticsService({
       config: {},
     } as any);
-    const api = new AddEditMonitorAPI({
+    const api = new UpsertMonitorAPI({
       syntheticsMonitorClient: new SyntheticsMonitorClient(syntheticsService, {} as any),
       request: {
         body: {},
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/add_monitor_api.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/upsert_monitor_api.ts
similarity index 98%
rename from x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/add_monitor_api.ts
rename to x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/upsert_monitor_api.ts
index f8c7fa9ed9b23..cf6a6431bb439 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/add_monitor_api.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/upsert_monitor_api.ts
@@ -49,12 +49,9 @@ export type CreateMonitorPayLoad = MonitorFields & {
   schedule?: number | MonitorFields['schedule'];
 };
 
-export class AddEditMonitorAPI {
-  routeContext: RouteContext;
+export class UpsertMonitorAPI {
   allPrivateLocations?: PrivateLocationAttributes[];
-  constructor(routeContext: RouteContext) {
-    this.routeContext = routeContext;
-  }
+  constructor(private readonly routeContext: RouteContext) {}
 
   async syncNewMonitor({
     id,
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/utils.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/utils.ts
index 2c58e868d827f..16f034e0d1a16 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/utils.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/add_monitor/utils.ts
@@ -6,7 +6,7 @@
  */
 
 import { SavedObjectsClientContract } from '@kbn/core-saved-objects-api-server';
-import { CreateMonitorPayLoad } from './add_monitor_api';
+import { CreateMonitorPayLoad } from './upsert_monitor_api';
 import { MonitorFields, SyntheticsMonitor } from '../../../../common/runtime_types';
 import { getPrivateLocations } from '../../../synthetics_service/get_private_locations';
 
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/edit_monitor.test.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/edit_monitor.test.ts
index cb50708c04eca..bbb8ff8e6ce3c 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/edit_monitor.test.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/edit_monitor.test.ts
@@ -6,9 +6,11 @@
  */
 
 import { loggerMock } from '@kbn/logging-mocks';
-import { syncEditedMonitor } from './edit_monitor';
+import { refreshInlineZip, syncEditedMonitor } from './edit_monitor';
 import { SavedObject, SavedObjectsClientContract, KibanaRequest } from '@kbn/core/server';
 import {
+  BrowserSensitiveSimpleFields,
+  ConfigKey,
   EncryptedSyntheticsMonitorAttributes,
   SyntheticsMonitor,
   SyntheticsMonitorWithSecretsAttributes,
@@ -17,6 +19,7 @@ import { SyntheticsService } from '../../synthetics_service/synthetics_service';
 import { SyntheticsMonitorClient } from '../../synthetics_service/synthetics_monitor/synthetics_monitor_client';
 import { mockEncryptedSO } from '../../synthetics_service/utils/mocks';
 import { SyntheticsServerSetup } from '../../types';
+import { unzipFile } from '../../common/unzip_project_code';
 
 jest.mock('../telemetry/monitor_upgrade_sender', () => ({
   sendTelemetryEvents: jest.fn(),
@@ -129,3 +132,250 @@ describe('syncEditedMonitor', () => {
     );
   });
 });
+
+describe('refreshInlineZip', () => {
+  it('refreshes the inline zip', async () => {
+    const normalized: SyntheticsMonitor = {
+      // @ts-expect-error extra field
+      type: 'browser',
+      // @ts-expect-error extra field
+      form_monitor_type: 'multistep',
+      enabled: true,
+      alert: { status: { enabled: true }, tls: { enabled: true } },
+      // @ts-expect-error extra field
+      schedule: { unit: 'm', number: '10' },
+      'service.name': '',
+      config_id: '7be61e81-a29a-439d-877b-9ff694c60d1b',
+      tags: [],
+      timeout: null,
+      name: 'test-again',
+      locations: [{ id: 'dev', label: 'Dev Service', isServiceManaged: true }],
+      namespace: 'default',
+      // @ts-expect-error extra field
+      origin: 'ui',
+      journey_id: '',
+      hash: '',
+      id: '7be61e81-a29a-439d-877b-9ff694c60d1b',
+      params: '',
+      max_attempts: 2,
+      project_id: '',
+      playwright_options: '',
+      __ui: { script_source: { is_generated_script: false, file_name: '' } },
+      'url.port': null,
+      'source.inline.script': `step('goto', ()=> page.goto('https://elastic.co'))
+        step('fail', () => {
+            // add a comment
+            throw Error('fail')
+        })`,
+      'source.project.content': `UEsDBBQACAAIAAiNSVgAAAAAAAAAAAAAAAARAAAAaW5saW5lLmpvdXJuZXkudHM1jsEKwjAQRO/5irmlgWDviuLFD4lhtZE2GzdbVEr/XVor7GmG92bTUFgUEx48SqaPR1UqHvQuFBUzbsID7Jn6UDXFtn6ydqQpVnswZoMam3KfMlmPZkIJd/KInJXe6nEVflUSjxIkDNVD6DlSVcwOxxMmg3WysXdWXgzueFoduyVobKda6r5ttw92ka1z5ofcQupX5G8CtBN+4SLCsvXOzMsdzBdQSwcIvqw1HaUAAADsAAAAUEsBAi0DFAAIAAgACI1JWL6sNR2lAAAA7AAAABEAAAAAAAAAAAAgAKSBAAAAAGlubGluZS5qb3VybmV5LnRzUEsFBgAAAAABAAEAPwAAAOQAAAAAAA==`,
+      playwright_text_assertion: '',
+      urls: '',
+      screenshots: 'on',
+      synthetics_args: [],
+      'filter_journeys.match': '',
+      'filter_journeys.tags': [],
+      ignore_https_errors: false,
+      throttling: {
+        value: { download: '5', upload: '3', latency: '20' },
+        id: 'default',
+        label: 'Default',
+      },
+      'ssl.certificate_authorities': '',
+      'ssl.certificate': '',
+      'ssl.key': '',
+      'ssl.key_passphrase': '',
+      'ssl.verification_mode': 'full',
+      'ssl.supported_protocols': ['TLSv1.1', 'TLSv1.2', 'TLSv1.3'],
+      revision: 2,
+    };
+    const previous: SavedObject<EncryptedSyntheticsMonitorAttributes> = {
+      id: '7be61e81-a29a-439d-877b-9ff694c60d1b',
+      type: 'synthetics-monitor',
+      namespaces: ['default'],
+      migrationVersion: undefined,
+      updated_at: '2024-02-09T17:40:17.708Z',
+      created_at: '2024-02-09T17:40:17.708Z',
+      version: 'WzQzMTAsMV0=',
+      attributes: {
+        // @ts-expect-error extra field
+        type: 'browser',
+        // @ts-expect-error extra field
+        form_monitor_type: 'multistep',
+        enabled: true,
+        // @ts-expect-error extra field
+        alert: { status: [Object], tls: [Object] },
+        // @ts-expect-error extra field
+        schedule: { unit: 'm', number: '10' },
+        'service.name': '',
+        config_id: '7be61e81-a29a-439d-877b-9ff694c60d1b',
+        tags: [],
+        timeout: null,
+        name: 'test-again',
+        namespace: 'default',
+        // @ts-expect-error extra field
+        origin: 'ui',
+        journey_id: '',
+        hash: '',
+        id: '7be61e81-a29a-439d-877b-9ff694c60d1b',
+        max_attempts: 2,
+        project_id: '',
+        playwright_options: '',
+        __ui: { script_source: [Object] },
+        'url.port': null,
+        playwright_text_assertion: '',
+        urls: '',
+        screenshots: 'on',
+        'filter_journeys.match': '',
+        'filter_journeys.tags': [],
+        ignore_https_errors: false,
+        throttling: { value: [Object], id: 'default', label: 'Default' },
+        'ssl.certificate_authorities': '',
+        'ssl.certificate': '',
+        'ssl.verification_mode': 'full',
+        'ssl.supported_protocols': ['TLSv1.1', 'TLSv1.2', 'TLSv1.3'],
+        revision: 1,
+      },
+      references: [],
+      managed: false,
+      coreMigrationVersion: '8.8.0',
+      typeMigrationVersion: '8.9.0',
+    };
+
+    // @ts-expect-error not testing logger functionality
+    const result = await refreshInlineZip(normalized, previous, jest.fn());
+    expect(typeof (result as BrowserSensitiveSimpleFields)[ConfigKey.SOURCE_PROJECT_CONTENT]).toBe(
+      'string'
+    );
+    expect(
+      await unzipFile((result as BrowserSensitiveSimpleFields)[ConfigKey.SOURCE_PROJECT_CONTENT])
+    ).toMatchInlineSnapshot(`
+      "import { journey, step, expect, mfa } from '@elastic/synthetics';
+
+      journey('inline', ({ page, context, browser, params, request }) => {
+      step('goto', ()=> page.goto('https://elastic.co'))
+              step('fail', () => {
+                  // add a comment
+                  throw Error('fail')
+              })
+      });"
+    `);
+    // the inline script was edited, and thus the new zip should be different
+    expect((result as BrowserSensitiveSimpleFields)[ConfigKey.SOURCE_PROJECT_CONTENT]).not.toEqual(
+      (normalized as BrowserSensitiveSimpleFields)[ConfigKey.SOURCE_PROJECT_CONTENT]
+    );
+    expect((result as BrowserSensitiveSimpleFields)[ConfigKey.SOURCE_INLINE])
+      .toMatchInlineSnapshot(`
+      "step('goto', ()=> page.goto('https://elastic.co'))
+              step('fail', () => {
+                  // add a comment
+                  throw Error('fail')
+              })"
+    `);
+  });
+
+  it('does nothing for lightweight monitors', async () => {
+    const normalized = {
+      type: 'http',
+      form_monitor_type: 'http',
+      enabled: true,
+      alert: { status: { enabled: true }, tls: { enabled: true } },
+      schedule: { number: '1', unit: 'm' },
+      'service.name': '',
+      config_id: '4b14793b-5916-42b4-946f-0eca7e09cf72',
+      tags: [],
+      timeout: '16',
+      name: 'http',
+      locations: [{ id: 'dev', label: 'Dev Service', isServiceManaged: true }],
+      namespace: 'default',
+      origin: 'ui',
+      journey_id: '',
+      hash: '',
+      id: '4b14793b-5916-42b4-946f-0eca7e09cf72',
+      params: '',
+      max_attempts: 2,
+      __ui: { is_tls_enabled: false },
+      urls: 'https://www.elastic.co',
+      max_redirects: '0',
+      'url.port': null,
+      password: '',
+      proxy_url: '',
+      proxy_headers: {},
+      'check.response.body.negative': [],
+      'check.response.body.positive': [],
+      'check.response.json': [],
+      'response.include_body': 'on_error',
+      'check.response.headers': {},
+      'response.include_headers': true,
+      'check.response.status': [],
+      'check.request.body': { type: 'text', value: '' },
+      'check.request.headers': { 'Content-Type': 'text/plain' },
+      'check.request.method': 'GET',
+      username: '',
+      mode: 'any',
+      'response.include_body_max_bytes': '1024',
+      ipv4: true,
+      ipv6: true,
+      'ssl.certificate_authorities': '',
+      'ssl.certificate': '',
+      'ssl.key': '',
+      'ssl.key_passphrase': '',
+      'ssl.verification_mode': 'full',
+      'ssl.supported_protocols': ['TLSv1.1', 'TLSv1.2', 'TLSv1.3'],
+      revision: 4,
+    };
+    const previous = {
+      id: '4b14793b-5916-42b4-946f-0eca7e09cf72',
+      type: 'synthetics-monitor',
+      namespaces: ['default'],
+      migrationVersion: undefined,
+      updated_at: '2024-02-09T20:02:56.660Z',
+      created_at: '2024-02-09T16:43:19.030Z',
+      version: 'WzUzNzcsMV0=',
+      attributes: {
+        type: 'http',
+        form_monitor_type: 'http',
+        enabled: true,
+        alert: { status: [Object], tls: [Object] },
+        schedule: { number: '1', unit: 'm' },
+        'service.name': '',
+        config_id: '4b14793b-5916-42b4-946f-0eca7e09cf72',
+        tags: [],
+        timeout: '16',
+        name: 'http',
+        locations: [[Object]],
+        namespace: 'default',
+        origin: 'ui',
+        journey_id: '',
+        hash: '',
+        id: '4b14793b-5916-42b4-946f-0eca7e09cf72',
+        max_attempts: 2,
+        __ui: { is_tls_enabled: false },
+        urls: 'https://www.elastic.co/',
+        max_redirects: '0',
+        'url.port': null,
+        proxy_url: '',
+        'response.include_body': 'on_error',
+        'response.include_headers': true,
+        'check.response.status': [],
+        'check.request.method': 'GET',
+        mode: 'any',
+        'response.include_body_max_bytes': '1024',
+        ipv4: true,
+        ipv6: true,
+        'ssl.certificate_authorities': '',
+        'ssl.certificate': '',
+        'ssl.verification_mode': 'full',
+        'ssl.supported_protocols': ['TLSv1.1', 'TLSv1.2', 'TLSv1.3'],
+        revision: 3,
+      },
+      references: [],
+      managed: false,
+      coreMigrationVersion: '8.8.0',
+      typeMigrationVersion: '8.9.0',
+    };
+
+    // @ts-expect-error not testing logger functionality
+    const result = await refreshInlineZip(normalized, previous, jest.fn());
+    expect((result as any)[ConfigKey.SOURCE_PROJECT_CONTENT]).toBeUndefined();
+  });
+});
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/edit_monitor.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/edit_monitor.ts
index d460b71037950..af26a816f730c 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/edit_monitor.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/edit_monitor.ts
@@ -10,7 +10,7 @@ import { SavedObjectsErrorHelpers } from '@kbn/core/server';
 import { isEmpty } from 'lodash';
 import { invalidOriginError } from './add_monitor';
 import { InvalidLocationError } from '../../synthetics_service/project_monitor/normalizers/common_fields';
-import { AddEditMonitorAPI, CreateMonitorPayLoad } from './add_monitor/add_monitor_api';
+import { UpsertMonitorAPI, CreateMonitorPayLoad } from './add_monitor/upsert_monitor_api';
 import { ELASTIC_MANAGED_LOCATIONS_DISABLED } from './add_monitor_project';
 import { getDecryptedMonitor } from '../../saved_objects/synthetics_monitor';
 import { getPrivateLocations } from '../../synthetics_service/get_private_locations';
@@ -33,9 +33,10 @@ import {
   formatTelemetryUpdateEvent,
 } from '../telemetry/monitor_upgrade_sender';
 import { formatSecrets, normalizeSecrets } from '../../synthetics_service/utils/secrets';
+import { SyntheticsServerSetup } from '../../types';
 import { mapSavedObjectToMonitor } from './formatters/saved_object_to_monitor';
+import { mapInlineToProjectFields } from '../../synthetics_service/utils/map_inline_to_project_fields';
 
-// Simplify return promise type and type it with runtime_types
 export const editSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () => ({
   method: 'PUT',
   path: SYNTHETICS_API_URLS.SYNTHETICS_MONITORS + '/{monitorId}',
@@ -73,7 +74,7 @@ export const editSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () => (
       return response.badRequest(getInvalidOriginError(monitor));
     }
 
-    const editMonitorAPI = new AddEditMonitorAPI(routeContext);
+    const editMonitorAPI = new UpsertMonitorAPI(routeContext);
     if (monitor.name) {
       const nameError = await editMonitorAPI.validateUniqueMonitorName(monitor.name, monitorId);
       if (nameError) {
@@ -219,6 +220,28 @@ const rollbackUpdate = async ({
   }
 };
 
+export const refreshInlineZip = async (
+  normalizedMonitor: SyntheticsMonitor,
+  previousMonitor: SavedObject<EncryptedSyntheticsMonitorAttributes>,
+  server: SyntheticsServerSetup
+) => {
+  const projectFields = await mapInlineToProjectFields({
+    monitorType: normalizedMonitor[ConfigKey.MONITOR_TYPE],
+    monitor: normalizedMonitor,
+    logger: server.logger,
+  });
+  return Object.assign(
+    {},
+    normalizedMonitor,
+    {
+      [ConfigKey.MONITOR_QUERY_ID]:
+        normalizedMonitor[ConfigKey.CUSTOM_HEARTBEAT_ID] || previousMonitor.id,
+      [ConfigKey.CONFIG_ID]: previousMonitor.id,
+    },
+    projectFields
+  );
+};
+
 export const syncEditedMonitor = async ({
   normalizedMonitor,
   decryptedPreviousMonitor,
@@ -232,13 +255,12 @@ export const syncEditedMonitor = async ({
 }) => {
   const { server, savedObjectsClient, syntheticsMonitorClient } = routeContext;
   try {
-    const monitorWithId = {
-      ...normalizedMonitor,
-      [ConfigKey.MONITOR_QUERY_ID]:
-        normalizedMonitor[ConfigKey.CUSTOM_HEARTBEAT_ID] || decryptedPreviousMonitor.id,
-      [ConfigKey.CONFIG_ID]: decryptedPreviousMonitor.id,
-    };
-    const formattedMonitor = formatSecrets(monitorWithId);
+    const monitorWithId = await refreshInlineZip(
+      normalizedMonitor,
+      decryptedPreviousMonitor,
+      server
+    );
+    const formattedMonitor = formatSecrets(monitorWithId as MonitorFields);
 
     const editedSOPromise = savedObjectsClient.update<MonitorFields>(
       syntheticsMonitorType,
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/inspect_monitor.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/inspect_monitor.ts
index 6b4687e2bea81..774ec2481a56c 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/inspect_monitor.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/inspect_monitor.ts
@@ -14,7 +14,7 @@ import { SYNTHETICS_API_URLS } from '../../../common/constants';
 import { DEFAULT_FIELDS } from '../../../common/constants/monitor_defaults';
 import { validateMonitor } from './monitor_validation';
 import { getPrivateLocationsForMonitor } from './add_monitor/utils';
-import { AddEditMonitorAPI } from './add_monitor/add_monitor_api';
+import { UpsertMonitorAPI } from './add_monitor/upsert_monitor_api';
 
 export const inspectSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () => ({
   method: 'POST',
@@ -65,7 +65,7 @@ export const inspectSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () =
     try {
       const newMonitorId = id ?? uuidV4();
 
-      const addMonitorAPI = new AddEditMonitorAPI(routeContext);
+      const addMonitorAPI = new UpsertMonitorAPI(routeContext);
 
       const monitorWithNamespace = addMonitorAPI.hydrateMonitorFields({
         normalizedMonitor,
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/monitor_validation.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/monitor_validation.ts
index ee4ccb7b7bf3e..e4550b1ba2eb3 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/monitor_validation.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/monitor_validation.ts
@@ -12,7 +12,7 @@ import { formatErrors } from '@kbn/securitysolution-io-ts-utils';
 import { omit } from 'lodash';
 import { schema } from '@kbn/config-schema';
 import { AlertConfigSchema } from '../../../common/runtime_types/monitor_management/alert_config_schema';
-import { CreateMonitorPayLoad } from './add_monitor/add_monitor_api';
+import { CreateMonitorPayLoad } from './add_monitor/upsert_monitor_api';
 import { flattenAndFormatObject } from '../../synthetics_service/project_monitor/normalizers/common_fields';
 import {
   BrowserFieldsCodec,
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/services/delete_monitor_api.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/services/delete_monitor_api.ts
index 4fc527f930832..d323b1b5bc773 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/services/delete_monitor_api.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/monitor_cruds/services/delete_monitor_api.ts
@@ -139,7 +139,6 @@ export class DeleteMonitorAPI {
           ...normalizedMonitor.attributes,
           id: normalizedMonitor.attributes[ConfigKey.MONITOR_QUERY_ID],
         })) as SyntheticsMonitorWithId[],
-        savedObjectsClient,
         spaceId
       );
 
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/run_once_monitor.test.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/run_once_monitor.test.ts
new file mode 100644
index 0000000000000..221cc4d093f59
--- /dev/null
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/run_once_monitor.test.ts
@@ -0,0 +1,68 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { ConfigKey } from '../../../common/runtime_types';
+import { unzipFile } from '../../common/unzip_project_code';
+import * as validator from '../monitor_cruds/monitor_validation';
+import { runOnceSyntheticsMonitorRoute } from './run_once_monitor';
+
+// Mocking the necessary modules
+jest.mock('../monitor_cruds/monitor_validation', () => ({
+  validateMonitor: jest.fn(),
+}));
+jest.mock('../monitor_cruds/add_monitor/utils', () => ({
+  getPrivateLocationsForMonitor: jest.fn(),
+}));
+
+describe('runOnceSyntheticsMonitorRoute', () => {
+  afterEach(() => {
+    jest.resetAllMocks();
+  });
+
+  it('will ship zipped project content for inline script monitors', async () => {
+    const monitorData = { type: 'browser', name: 'test monitor' };
+    jest.spyOn(validator, 'validateMonitor').mockReturnValue({
+      decodedMonitor: {
+        // @ts-ignore just testing zip
+        type: 'browser',
+        [ConfigKey.SOURCE_INLINE]: 'step("goto", () => page.goto("http://example.com"))',
+        urls: 'http://example.com',
+        'url.port': null,
+      },
+      valid: true,
+    });
+
+    const testNowConfigsMock = jest.fn() as any;
+    testNowConfigsMock.mockResolvedValue([null, undefined]);
+    await runOnceSyntheticsMonitorRoute().handler({
+      // @ts-ignore just testing zip
+      request: {
+        params: { monitorId: 'test-monitor-id' },
+        body: monitorData,
+      },
+      response: {} as any,
+      server: {} as any,
+      syntheticsMonitorClient: {
+        testNowConfigs: testNowConfigsMock,
+      } as any,
+      savedObjectsClient: {} as any,
+    });
+
+    expect(testNowConfigsMock).toHaveBeenCalledTimes(1);
+    const monitor = testNowConfigsMock.mock.calls[0][0].monitor;
+    expect(monitor).toBeDefined();
+    expect(monitor[ConfigKey.SOURCE_INLINE]).toBeUndefined();
+    expect(monitor[ConfigKey.SOURCE_PROJECT_CONTENT]).toBeDefined();
+    expect(await unzipFile(monitor[ConfigKey.SOURCE_PROJECT_CONTENT])).toMatchInlineSnapshot(`
+      "import { journey, step, expect, mfa } from '@elastic/synthetics';
+
+      journey('inline', ({ page, context, browser, params, request }) => {
+      step(\\"goto\\", () => page.goto(\\"http://example.com\\"))
+      });"
+    `);
+  });
+});
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/run_once_monitor.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/run_once_monitor.ts
index 2af3a10f39750..d98810f14c62a 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/run_once_monitor.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/run_once_monitor.ts
@@ -6,13 +6,14 @@
  */
 import { schema } from '@kbn/config-schema';
 import { DEFAULT_SPACE_ID } from '@kbn/spaces-plugin/common';
-import { isEmpty } from 'lodash';
+import { isEmpty, omit } from 'lodash';
 import { PrivateLocationAttributes } from '../../runtime_types/private_locations';
 import { getPrivateLocationsForMonitor } from '../monitor_cruds/add_monitor/utils';
 import { SyntheticsRestApiRouteFactory } from '../types';
 import { ConfigKey, MonitorFields } from '../../../common/runtime_types';
 import { SYNTHETICS_API_URLS } from '../../../common/constants';
 import { validateMonitor } from '../monitor_cruds/monitor_validation';
+import { mapInlineToProjectFields } from '../../synthetics_service/utils/map_inline_to_project_fields';
 
 export const runOnceSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () => ({
   method: 'POST',
@@ -30,13 +31,13 @@ export const runOnceSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () =
     syntheticsMonitorClient,
     savedObjectsClient,
   }): Promise<any> => {
-    const monitor = request.body as MonitorFields;
+    const requestFields = request.body as MonitorFields;
     const { monitorId } = request.params;
-    if (isEmpty(monitor)) {
+    if (isEmpty(requestFields)) {
       return response.badRequest({ body: { message: 'Monitor data is empty.' } });
     }
 
-    const validationResult = validateMonitor(monitor);
+    const validationResult = validateMonitor(requestFields);
 
     const spaceId = server.spaces?.spacesService.getSpaceId(request) ?? DEFAULT_SPACE_ID;
 
@@ -51,17 +52,26 @@ export const runOnceSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () =
       decodedMonitor
     );
 
+    const monitorFields = {
+      ...decodedMonitor,
+      [ConfigKey.CONFIG_ID]: monitorId,
+      [ConfigKey.MONITOR_QUERY_ID]: monitorId,
+    } as MonitorFields;
+    const zippedProjectFields = await mapInlineToProjectFields({
+      monitorType: decodedMonitor.type,
+      monitor: monitorFields,
+      logger: server.logger,
+    });
+    const monitor = omit(
+      Object.assign(monitorFields, zippedProjectFields),
+      ConfigKey.SOURCE_INLINE
+    ) as MonitorFields;
     const [, errors] = await syntheticsMonitorClient.testNowConfigs(
       {
-        monitor: {
-          ...decodedMonitor,
-          [ConfigKey.CONFIG_ID]: monitorId,
-          [ConfigKey.MONITOR_QUERY_ID]: monitorId,
-        } as MonitorFields,
+        monitor,
         id: monitorId,
         testRunId: monitorId,
       },
-      savedObjectsClient,
       privateLocations,
       spaceId,
       true
@@ -71,6 +81,6 @@ export const runOnceSyntheticsMonitorRoute: SyntheticsRestApiRouteFactory = () =
       return { errors };
     }
 
-    return monitor;
+    return requestFields;
   },
 });
diff --git a/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/test_now_monitor.ts b/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/test_now_monitor.ts
index d1a1513ae85c8..48494c54b638f 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/test_now_monitor.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/routes/synthetics_service/test_now_monitor.ts
@@ -16,6 +16,7 @@ import { ConfigKey, MonitorFields } from '../../../common/runtime_types';
 import { SYNTHETICS_API_URLS } from '../../../common/constants';
 import { normalizeSecrets } from '../../synthetics_service/utils/secrets';
 import { getPrivateLocationsForMonitor } from '../monitor_cruds/add_monitor/utils';
+import { dropInlineScriptForTransmission } from '../../synthetics_service/utils/map_inline_to_project_fields';
 import { getMonitorNotFoundResponse } from './service_errors';
 
 export const testNowMonitorRoute: SyntheticsRestApiRouteFactory<TestNowResponse> = () => ({
@@ -54,11 +55,10 @@ export const triggerTestNow = async (
 
     const [, errors] = await syntheticsMonitorClient.testNowConfigs(
       {
-        monitor: normalizedMonitor.attributes as MonitorFields,
+        monitor: dropInlineScriptForTransmission(normalizedMonitor.attributes as MonitorFields),
         id: monitorId,
         testRunId,
       },
-      savedObjectsClient,
       privateLocations,
       spaceId
     );
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/private_formatters/format_synthetics_policy.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/private_formatters/format_synthetics_policy.ts
index 78cbc2d4a0790..4ddfd32d68ab3 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/private_formatters/format_synthetics_policy.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/private_formatters/format_synthetics_policy.ts
@@ -6,7 +6,7 @@
  */
 
 import { NewPackagePolicy } from '@kbn/fleet-plugin/common';
-import { cloneDeep } from 'lodash';
+import { cloneDeep, omit } from 'lodash';
 import { processorsFormatter } from './processors_formatter';
 import { LegacyConfigKey } from '../../../../common/constants/monitor_management';
 import { ConfigKey, MonitorTypeEnum, MonitorFields } from '../../../../common/runtime_types';
@@ -80,5 +80,9 @@ export const formatSyntheticsPolicy = (
     throttling.value = throttlingFormatter?.(config, ConfigKey.THROTTLING_CONFIG);
   }
 
-  return { formattedPolicy, hasDataStream: Boolean(dataStream), hasInput: Boolean(currentInput) };
+  return {
+    formattedPolicy: omit(formattedPolicy, [ConfigKey.SOURCE_INLINE]) as NewPackagePolicy,
+    hasDataStream: Boolean(dataStream),
+    hasInput: Boolean(currentInput),
+  };
 };
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/public_formatters/format_configs.test.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/public_formatters/format_configs.test.ts
index 979db50dee6d4..262e577c48e5c 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/public_formatters/format_configs.test.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/public_formatters/format_configs.test.ts
@@ -22,7 +22,9 @@ import {
   ScheduleUnit,
   SyntheticsMonitor,
   VerificationMode,
+  BrowserSensitiveSimpleFields,
 } from '../../../../common/runtime_types';
+import { inlineToProjectZip } from '../../../common/inline_to_zip';
 
 const testHTTPConfig: Partial<MonitorFields> = {
   type: 'http' as MonitorTypeEnum,
@@ -355,66 +357,13 @@ describe('formatHeartbeatRequest', () => {
     });
   });
 
-  it('sets project fields as null when project id is not defined', () => {
-    const monitorId = 'test-monitor-id';
-    const monitor = { ...testBrowserConfig, project_id: undefined } as SyntheticsMonitor;
-    const actual = formatHeartbeatRequest({
-      monitor,
-      configId: monitorId,
-      heartbeatId: monitorId,
-      spaceId: 'test-space-id',
-    });
-
-    expect(actual).toEqual({
-      ...monitor,
-      id: monitorId,
-      fields: {
-        config_id: monitorId,
-        'monitor.project.name': undefined,
-        'monitor.project.id': undefined,
-        run_once: undefined,
-        test_run_id: undefined,
-        meta: {
-          space_id: 'test-space-id',
-        },
-      },
-      fields_under_root: true,
-    });
-  });
-
-  it('sets project fields as null when project id is empty', () => {
-    const monitorId = 'test-monitor-id';
-    const monitor = { ...testBrowserConfig, project_id: '' } as SyntheticsMonitor;
-    const actual = formatHeartbeatRequest({
-      monitor,
-      configId: monitorId,
-      heartbeatId: monitorId,
-      spaceId: 'test-space-id',
-    });
-
-    expect(actual).toEqual({
-      ...monitor,
-      id: monitorId,
-      fields: {
-        config_id: monitorId,
-        'monitor.project.name': undefined,
-        'monitor.project.id': undefined,
-        run_once: undefined,
-        test_run_id: undefined,
-        meta: {
-          space_id: 'test-space-id',
-        },
-      },
-      fields_under_root: true,
-    });
-  });
-
-  it('supports run once', () => {
+  it('supports test_run_id', () => {
     const monitorId = 'test-monitor-id';
+    const testRunId = 'beep';
     const actual = formatHeartbeatRequest({
       monitor: testBrowserConfig as SyntheticsMonitor,
       configId: monitorId,
-      runOnce: true,
+      testRunId,
       heartbeatId: monitorId,
       spaceId: 'test-space-id',
     });
@@ -426,8 +375,8 @@ describe('formatHeartbeatRequest', () => {
         config_id: monitorId,
         'monitor.project.name': testBrowserConfig.project_id,
         'monitor.project.id': testBrowserConfig.project_id,
-        run_once: true,
-        test_run_id: undefined,
+        run_once: undefined,
+        test_run_id: testRunId,
         meta: {
           space_id: 'test-space-id',
         },
@@ -436,11 +385,11 @@ describe('formatHeartbeatRequest', () => {
     });
   });
 
-  it('supports test_run_id', () => {
+  it('does not append project data', () => {
     const monitorId = 'test-monitor-id';
     const testRunId = 'beep';
     const actual = formatHeartbeatRequest({
-      monitor: testBrowserConfig as SyntheticsMonitor,
+      monitor: { ...testBrowserConfig, params: '' } as SyntheticsMonitor,
       configId: monitorId,
       testRunId,
       heartbeatId: monitorId,
@@ -449,6 +398,7 @@ describe('formatHeartbeatRequest', () => {
 
     expect(actual).toEqual({
       ...testBrowserConfig,
+      params: '',
       id: monitorId,
       fields: {
         config_id: monitorId,
@@ -462,33 +412,50 @@ describe('formatHeartbeatRequest', () => {
       },
       fields_under_root: true,
     });
+    expect(
+      (actual as BrowserSensitiveSimpleFields)[ConfigKey.SOURCE_PROJECT_CONTENT]
+    ).toBeUndefined();
+    expect((actual as BrowserSensitiveSimpleFields)[ConfigKey.SOURCE_INLINE])
+      .toMatchInlineSnapshot(`
+      "step('Go to https://www.google.com/', async () => {
+        await page.goto('https://www.google.com/');
+      });"
+    `);
   });
 
-  it('supports empty params', () => {
+  it('retains project string if there is no inline content', async () => {
     const monitorId = 'test-monitor-id';
-    const testRunId = 'beep';
+    const projectZipInput = await inlineToProjectZip(
+      "step('Go to https://www.google.com/', async () => {\n  await page.goto('https://www.google.com/');\n});",
+      monitorId,
+      jest.fn() as any
+    );
     const actual = formatHeartbeatRequest({
-      monitor: { ...testBrowserConfig, params: '' } as SyntheticsMonitor,
+      monitor: {
+        ...testBrowserConfig,
+        [ConfigKey.SOURCE_INLINE]: '',
+        [ConfigKey.SOURCE_PROJECT_CONTENT]: projectZipInput,
+      } as SyntheticsMonitor,
       configId: monitorId,
-      testRunId,
       heartbeatId: monitorId,
       spaceId: 'test-space-id',
     });
 
     expect(actual).toEqual({
       ...testBrowserConfig,
-      params: '',
       id: monitorId,
       fields: {
         config_id: monitorId,
         'monitor.project.name': testBrowserConfig.project_id,
         'monitor.project.id': testBrowserConfig.project_id,
         run_once: undefined,
-        test_run_id: testRunId,
+        test_run_id: undefined,
         meta: {
           space_id: 'test-space-id',
         },
       },
+      [ConfigKey.SOURCE_INLINE]: '',
+      [ConfigKey.SOURCE_PROJECT_CONTENT]: projectZipInput,
       fields_under_root: true,
     });
   });
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/public_formatters/format_configs.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/public_formatters/format_configs.ts
index d9c0821154990..b4abe1c8bd7a1 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/public_formatters/format_configs.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/formatters/public_formatters/format_configs.ts
@@ -5,7 +5,7 @@
  * 2.0.
  */
 
-import { isEmpty, isNil, omitBy } from 'lodash';
+import { isEmpty, isNil, omit, omitBy } from 'lodash';
 import { Logger } from '@kbn/logging';
 import { replaceStringWithParams } from '../formatting_utils';
 import { PARAMS_KEYS_TO_SKIP } from '../common';
@@ -89,6 +89,13 @@ export interface ConfigData {
   spaceId: string;
 }
 
+function stripInlineScript(config: BrowserFields): BrowserFields {
+  if (config?.[ConfigKey.SOURCE_PROJECT_CONTENT] && config?.[ConfigKey.SOURCE_INLINE]) {
+    return omit(config, ConfigKey.SOURCE_INLINE) as BrowserFields;
+  }
+  return config;
+}
+
 export const formatHeartbeatRequest = (
   { monitor, configId, heartbeatId, runOnce, testRunId, spaceId }: Omit<ConfigData, 'params'>,
   params?: string
@@ -101,7 +108,7 @@ export const formatHeartbeatRequest = (
   const { labels } = monitor;
 
   return {
-    ...monitor,
+    ...stripInlineScript(monitor as BrowserFields),
     id: heartbeatIdT,
     fields: {
       config_id: configId,
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/private_location/synthetics_private_location.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/private_location/synthetics_private_location.ts
index 9ed34399e74f2..09ba90695ea7f 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/private_location/synthetics_private_location.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/private_location/synthetics_private_location.ts
@@ -158,7 +158,6 @@ export class SyntheticsPrivateLocation {
               `Unable to find Synthetics private location for agentId ${privateLocation.id}`
             );
           }
-
           const newPolicy = await this.generateNewPolicy(
             config,
             location,
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_monitor/synthetics_monitor_client.test.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_monitor/synthetics_monitor_client.test.ts
index 594621b3b1ab4..bdd5848900fef 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_monitor/synthetics_monitor_client.test.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_monitor/synthetics_monitor_client.test.ts
@@ -5,7 +5,7 @@
  * 2.0.
  */
 import { loggerMock } from '@kbn/logging-mocks';
-import { SavedObjectsClientContract, CoreStart } from '@kbn/core/server';
+import { CoreStart } from '@kbn/core/server';
 import { coreMock } from '@kbn/core/server/mocks';
 import { SyntheticsMonitorClient } from './synthetics_monitor_client';
 import { SyntheticsService } from '../synthetics_service';
@@ -42,10 +42,6 @@ describe('SyntheticsMonitorClient', () => {
   const mockEsClient = {
     search: jest.fn(),
   };
-  const savedObjectsClientMock = {
-    bulkUpdate: jest.fn(),
-    get: jest.fn(),
-  } as unknown as SavedObjectsClientContract;
 
   const logger = loggerMock.create();
 
@@ -204,11 +200,7 @@ describe('SyntheticsMonitorClient', () => {
     client.privateLocationAPI.deleteMonitors = jest.fn();
     syntheticsService.deleteConfigs = jest.fn();
 
-    await client.deleteMonitors(
-      [monitor as unknown as SyntheticsMonitorWithId],
-      savedObjectsClientMock,
-      'test-space'
-    );
+    await client.deleteMonitors([monitor as unknown as SyntheticsMonitorWithId], 'test-space');
 
     expect(syntheticsService.deleteConfigs).toHaveBeenCalledTimes(1);
     expect(client.privateLocationAPI.deleteMonitors).toHaveBeenCalledTimes(1);
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_monitor/synthetics_monitor_client.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_monitor/synthetics_monitor_client.ts
index b0f9cd20211b3..566f43ac71fb3 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_monitor/synthetics_monitor_client.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_monitor/synthetics_monitor_client.ts
@@ -4,7 +4,8 @@
  * 2.0; you may not use this file except in compliance with the Elastic License
  * 2.0.
  */
-import { SavedObject, SavedObjectsClientContract, SavedObjectsFindResult } from '@kbn/core/server';
+
+import { SavedObject, SavedObjectsFindResult } from '@kbn/core/server';
 import { EncryptedSavedObjectsPluginStart } from '@kbn/encrypted-saved-objects-plugin/server';
 import { SyntheticsServerSetup } from '../../types';
 import { syntheticsMonitorType } from '../../../common/types/saved_objects';
@@ -162,11 +163,7 @@ export class SyntheticsMonitorClient {
 
     return { failedPolicyUpdates, publicSyncErrors };
   }
-  async deleteMonitors(
-    monitors: SyntheticsMonitorWithId[],
-    savedObjectsClient: SavedObjectsClientContract,
-    spaceId: string
-  ) {
+  async deleteMonitors(monitors: SyntheticsMonitorWithId[], spaceId: string) {
     const privateDeletePromise = this.privateLocationAPI.deleteMonitors(monitors, spaceId);
 
     const publicDeletePromise = this.syntheticsService.deleteConfigs(
@@ -179,7 +176,6 @@ export class SyntheticsMonitorClient {
 
   async testNowConfigs(
     monitor: { monitor: MonitorFields; id: string; testRunId: string },
-    savedObjectsClient: SavedObjectsClientContract,
     allPrivateLocations: PrivateLocationAttributes[],
     spaceId: string,
     runOnce?: true
@@ -220,7 +216,7 @@ export class SyntheticsMonitorClient {
       }
     }
 
-    const newPolicies = this.privateLocationAPI.createPackagePolicies(
+    const newPoliciesPromise = this.privateLocationAPI.createPackagePolicies(
       privateConfig ? [privateConfig] : [],
       allPrivateLocations,
       spaceId,
@@ -228,9 +224,9 @@ export class SyntheticsMonitorClient {
       runOnce
     );
 
-    const syncErrors = this.syntheticsService.runOnceConfigs(publicConfig);
+    const syncErrorsPromise = this.syntheticsService.runOnceConfigs(publicConfig);
 
-    return await Promise.all([newPolicies, syncErrors]);
+    return await Promise.all([newPoliciesPromise, syncErrorsPromise]);
   }
 
   hasPrivateLocations(previousMonitor: SavedObject<EncryptedSyntheticsMonitorAttributes>) {
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_service.test.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_service.test.ts
index fdc41831e8afd..d8fa277606402 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_service.test.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_service.test.ts
@@ -10,9 +10,9 @@ import { coreMock, savedObjectsClientMock } from '@kbn/core/server/mocks';
 import { CoreStart } from '@kbn/core/server';
 import { SyntheticsService } from './synthetics_service';
 import { loggerMock } from '@kbn/logging-mocks';
-import axios, { AxiosResponse } from 'axios';
+import axios, { AxiosRequestConfig, AxiosResponse } from 'axios';
 import times from 'lodash/times';
-import { LocationStatus, HeartbeatConfig } from '../../common/runtime_types';
+import { LocationStatus, HeartbeatConfig, ConfigKey } from '../../common/runtime_types';
 import { mockEncryptedSO } from './utils/mocks';
 import * as apiKeys from './get_api_key';
 import { SyntheticsServerSetup } from '../types';
@@ -356,6 +356,60 @@ describe('SyntheticsService', () => {
       );
     });
 
+    it('does not add zip to inline source', async () => {
+      const { service, locations } = getMockedService();
+
+      serverMock.encryptedSavedObjects = mockEncryptedSO({
+        monitors: [
+          {
+            attributes: {
+              ...getFakePayload([locations[0]]),
+              [ConfigKey.MONITOR_TYPE]: 'browser',
+              [ConfigKey.SOURCE_INLINE]: `step('goto', () => page.goto('https://elastic.co'))`,
+            },
+          },
+        ],
+      });
+
+      (axios as jest.MockedFunction<typeof axios>).mockResolvedValue({} as AxiosResponse);
+
+      await service.pushConfigs();
+
+      expect(axios).toHaveBeenCalledTimes(1);
+      const mockArg = (axios as jest.MockedFunction<typeof axios>).mock.calls[0][0];
+      const projectContent = (mockArg as AxiosRequestConfig).data.monitors[0].streams[0][
+        ConfigKey.SOURCE_PROJECT_CONTENT
+      ];
+      expect(projectContent).not.toBeDefined();
+    });
+
+    it('does not push a zip if inline content is missing', async () => {
+      const { service, locations } = getMockedService();
+
+      serverMock.encryptedSavedObjects = mockEncryptedSO({
+        monitors: [
+          {
+            attributes: {
+              ...getFakePayload([locations[0]]),
+              [ConfigKey.MONITOR_TYPE]: 'browser',
+              [ConfigKey.SOURCE_INLINE]: undefined,
+            },
+          },
+        ],
+      });
+
+      (axios as jest.MockedFunction<typeof axios>).mockResolvedValue({} as AxiosResponse);
+
+      await service.pushConfigs();
+
+      expect(axios).toHaveBeenCalledTimes(1);
+      const mockArg = (axios as jest.MockedFunction<typeof axios>).mock.calls[0][0];
+      const projectContent = (mockArg as AxiosRequestConfig).data.monitors[0].streams[0][
+        ConfigKey.SOURCE_PROJECT_CONTENT
+      ];
+      expect(projectContent).toBeUndefined();
+    });
+
     it.each([
       [true, 'Cannot sync monitors with the Synthetics service. License is expired.'],
       [
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_service.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_service.ts
index be72ca4d9a496..89a2fd00c1249 100644
--- a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_service.ts
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/synthetics_service.ts
@@ -16,8 +16,8 @@ import {
 } from '@kbn/task-manager-plugin/server';
 import { DEFAULT_SPACE_ID } from '@kbn/spaces-plugin/common';
 import { ALL_SPACES_ID } from '@kbn/spaces-plugin/common/constants';
-import pMap from 'p-map';
 import moment from 'moment';
+import pMap from 'p-map';
 import { registerCleanUpTask } from './private_location/clean_up_task';
 import { SyntheticsServerSetup } from '../types';
 import { syntheticsMonitorType, syntheticsParamType } from '../../common/types/saved_objects';
@@ -46,6 +46,7 @@ import {
   formatMonitorConfigFields,
   mixParamsWithGlobalParams,
 } from './formatters/public_formatters/format_configs';
+import { dropInlineScriptForTransmission } from './utils/map_inline_to_project_fields';
 
 const SYNTHETICS_SERVICE_SYNC_MONITORS_TASK_TYPE =
   'UPTIME:SyntheticsService:Sync-Saved-Monitor-Objects';
@@ -420,7 +421,7 @@ export class SyntheticsService {
             );
 
             const syncErrors = await this.apiClient.syncMonitors({
-              monitors: locMonitors,
+              monitors: locMonitors.map(dropInlineScriptForTransmission),
               output,
               license,
               location,
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/utils/map_inline_to_project_fields.test.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/utils/map_inline_to_project_fields.test.ts
new file mode 100644
index 0000000000000..f25668606e47d
--- /dev/null
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/utils/map_inline_to_project_fields.test.ts
@@ -0,0 +1,147 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { Logger } from '@kbn/logging';
+import { ConfigKey, MonitorFields } from '../../../common/runtime_types';
+import { unzipFile } from '../../common/unzip_project_code';
+import {
+  dropInlineScriptForTransmission,
+  mapInlineToProjectFields,
+} from './map_inline_to_project_fields';
+import * as inlineToZip from '../../common/inline_to_zip';
+
+describe('dropInlineScriptForTransmission', () => {
+  it('omits the inline script if there is project content available', () => {
+    expect(
+      dropInlineScriptForTransmission({
+        [ConfigKey.SOURCE_INLINE]: 'this monitor has project content',
+        [ConfigKey.SOURCE_PROJECT_CONTENT]: 'so we should remove the inline script',
+        [ConfigKey.MONITOR_TYPE]: 'browser',
+        [ConfigKey.MONITOR_SOURCE_TYPE]: 'ui',
+      } as MonitorFields)
+    ).toEqual({
+      [ConfigKey.SOURCE_PROJECT_CONTENT]: 'so we should remove the inline script',
+      [ConfigKey.MONITOR_TYPE]: 'browser',
+      [ConfigKey.MONITOR_SOURCE_TYPE]: 'ui',
+    });
+  });
+
+  it('returns the original monitor if there is no project content', () => {
+    expect(
+      dropInlineScriptForTransmission({
+        [ConfigKey.SOURCE_INLINE]: 'this is an old monitor that has no zip content',
+        [ConfigKey.MONITOR_TYPE]: 'browser',
+        [ConfigKey.MONITOR_SOURCE_TYPE]: 'ui',
+      } as MonitorFields)
+    ).toEqual({
+      [ConfigKey.SOURCE_INLINE]: 'this is an old monitor that has no zip content',
+      [ConfigKey.MONITOR_TYPE]: 'browser',
+      [ConfigKey.MONITOR_SOURCE_TYPE]: 'ui',
+    });
+  });
+
+  it('returns the original monitor if it is not of type `browser`', () => {
+    expect(
+      dropInlineScriptForTransmission({
+        [ConfigKey.MONITOR_TYPE]: 'http',
+        [ConfigKey.MONITOR_SOURCE_TYPE]: 'ui',
+      } as MonitorFields)
+    ).toEqual({
+      [ConfigKey.MONITOR_TYPE]: 'http',
+      [ConfigKey.MONITOR_SOURCE_TYPE]: 'ui',
+    });
+  });
+
+  it('returns the original monitor if it is not a UI monitor', () => {
+    expect(
+      dropInlineScriptForTransmission({
+        [ConfigKey.SOURCE_PROJECT_CONTENT]: 'so we should remove the inline script',
+        [ConfigKey.MONITOR_TYPE]: 'browser',
+        [ConfigKey.MONITOR_SOURCE_TYPE]: 'project',
+      } as MonitorFields)
+    ).toEqual({
+      [ConfigKey.SOURCE_PROJECT_CONTENT]: 'so we should remove the inline script',
+      [ConfigKey.MONITOR_TYPE]: 'browser',
+      [ConfigKey.MONITOR_SOURCE_TYPE]: 'project',
+    });
+  });
+});
+
+describe('mapInlineToProjectFields', () => {
+  let logger: Logger;
+
+  beforeEach(() => {
+    logger = {
+      debug: jest.fn(),
+      info: jest.fn(),
+      warn: jest.fn(),
+      error: jest.fn(),
+    } as unknown as Logger;
+  });
+
+  it.each(['http', 'tcp', 'icmp'])(
+    'should return an empty object if the monitor type is not browser',
+    async (monitorType) => {
+      const result = await mapInlineToProjectFields({
+        monitorType,
+        monitor: {},
+        logger: logger as any,
+      });
+      expect(result).toEqual({});
+    }
+  );
+
+  it('should return an empty object if the inline script is empty', async () => {
+    const result = await mapInlineToProjectFields({
+      monitorType: 'browser',
+      monitor: { [ConfigKey.SOURCE_PROJECT_CONTENT]: 'foo' },
+      logger: logger as any,
+    });
+    expect(result).toEqual({});
+  });
+
+  it.each([true, false])(
+    'should zip the source inline and return it as project content',
+    async (includeInlineScript) => {
+      const expectedInlineScript = `step('goto', () => page.goto('https://elastic.co'))`;
+      const result = await mapInlineToProjectFields({
+        monitorType: 'browser',
+        monitor: {
+          [ConfigKey.SOURCE_INLINE]: expectedInlineScript,
+        },
+        logger: logger as any,
+        includeInlineScript,
+      });
+      expect(result[ConfigKey.SOURCE_INLINE]).toEqual(
+        includeInlineScript ? expectedInlineScript : undefined
+      );
+      expect(await unzipFile(result[ConfigKey.SOURCE_PROJECT_CONTENT] ?? ''))
+        .toMatchInlineSnapshot(`
+      "import { journey, step, expect, mfa } from '@elastic/synthetics';
+
+      journey('inline', ({ page, context, browser, params, request }) => {
+      step('goto', () => page.goto('https://elastic.co'))
+      });"
+    `);
+    }
+  );
+
+  it('should return the inline script if the zipping fails', async () => {
+    jest.spyOn(inlineToZip, 'inlineToProjectZip').mockImplementationOnce(async () => {
+      throw new Error('Failed to zip');
+    });
+
+    const result = await mapInlineToProjectFields({
+      monitorType: 'browser',
+      monitor: {
+        [ConfigKey.SOURCE_INLINE]: 'foo',
+      },
+      logger: logger as any,
+    });
+    expect(result[ConfigKey.SOURCE_INLINE]).toEqual('foo');
+  });
+});
diff --git a/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/utils/map_inline_to_project_fields.ts b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/utils/map_inline_to_project_fields.ts
new file mode 100644
index 0000000000000..6cee9b137b7b0
--- /dev/null
+++ b/x-pack/plugins/observability_solution/synthetics/server/synthetics_service/utils/map_inline_to_project_fields.ts
@@ -0,0 +1,65 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import { Logger } from '@kbn/logging';
+import { omit } from 'lodash';
+import { BrowserSimpleFields, ConfigKey, MonitorFields } from '../../../common/runtime_types';
+import { inlineToProjectZip } from '../../common/inline_to_zip';
+
+interface MapInlineToProjectFieldsArgs {
+  monitorType: string;
+  monitor: unknown;
+  logger: Logger;
+  includeInlineScript?: boolean;
+}
+
+export async function mapInlineToProjectFields({
+  monitorType,
+  monitor,
+  logger,
+  includeInlineScript,
+}: MapInlineToProjectFieldsArgs) {
+  if (monitorType !== 'browser' || !monitor) return {};
+  const asBrowserMonitor = monitor as BrowserSimpleFields;
+  const inlineScript = asBrowserMonitor?.[ConfigKey.SOURCE_INLINE];
+  if (!inlineScript) return {};
+  try {
+    const projectZip = await inlineToProjectZip(
+      inlineScript,
+      asBrowserMonitor?.[ConfigKey.CONFIG_ID],
+      logger
+    );
+    if (includeInlineScript)
+      return {
+        [ConfigKey.SOURCE_INLINE]: inlineScript,
+        [ConfigKey.SOURCE_PROJECT_CONTENT]: projectZip,
+      };
+    return {
+      [ConfigKey.SOURCE_PROJECT_CONTENT]: projectZip,
+    };
+  } catch (e) {
+    logger.error(e);
+  }
+
+  return {
+    [ConfigKey.SOURCE_INLINE]: inlineScript,
+  };
+}
+
+/**
+ * We don't transmit the inline script in `source.inline.script` field anymore, because JS parsing on the backend
+ * can break on certain characters. The procedure for handling project content (the default behavior in the absence
+ * of the inline script data) is not susceptible to this issue.
+ *
+ * See https://github.com/elastic/kibana/issues/169963 for more information.
+ */
+export const dropInlineScriptForTransmission = (monitor: MonitorFields): MonitorFields => {
+  if ((monitor as MonitorFields)[ConfigKey.SOURCE_PROJECT_CONTENT]) {
+    return omit(monitor, ConfigKey.SOURCE_INLINE) as MonitorFields;
+  }
+  return monitor;
+};
diff --git a/x-pack/test/api_integration/apis/synthetics/add_monitor_public_api.ts b/x-pack/test/api_integration/apis/synthetics/add_monitor_public_api.ts
index 082d1aebd6d76..a33ad2ff07473 100644
--- a/x-pack/test/api_integration/apis/synthetics/add_monitor_public_api.ts
+++ b/x-pack/test/api_integration/apis/synthetics/add_monitor_public_api.ts
@@ -9,8 +9,11 @@ import { v4 as uuidv4 } from 'uuid';
 
 import { DEFAULT_FIELDS } from '@kbn/synthetics-plugin/common/constants/monitor_defaults';
 import { LOCATION_REQUIRED_ERROR } from '@kbn/synthetics-plugin/server/routes/monitor_cruds/monitor_validation';
-import { FtrProviderContext } from '../../ftr_provider_context';
+import { ConfigKey } from '@kbn/synthetics-plugin/common/runtime_types';
+import { omit } from 'lodash';
+import { unzipFile } from '@kbn/synthetics-plugin/server/common/unzip_project_code';
 import { addMonitorAPIHelper, omitMonitorKeys } from './add_monitor';
+import { FtrProviderContext } from '../../ftr_provider_context';
 
 export default function ({ getService }: FtrProviderContext) {
   describe('AddNewMonitorsPublicAPI', function () {
@@ -253,13 +256,17 @@ export default function ({ getService }: FtrProviderContext) {
         };
         const { body: result } = await addMonitorAPI(monitor);
 
-        expect(result).eql(
+        expect(omit(result, ConfigKey.SOURCE_PROJECT_CONTENT)).eql(
           omitMonitorKeys({
             ...defaultFields,
             ...monitor,
             locations: [localLoc],
           })
         );
+        expect(result[ConfigKey.SOURCE_PROJECT_CONTENT]).to.be.a('string');
+        expect(await unzipFile(result[ConfigKey.SOURCE_PROJECT_CONTENT])).to.contain(
+          monitor[ConfigKey.SOURCE_INLINE]
+        );
       });
 
       it('base browser monitor with inline_script', async () => {
@@ -271,13 +278,17 @@ export default function ({ getService }: FtrProviderContext) {
         };
         const { body: result } = await addMonitorAPI(monitor);
 
-        expect(result).eql(
+        expect(omit(result, ConfigKey.SOURCE_PROJECT_CONTENT)).eql(
           omitMonitorKeys({
             ...defaultFields,
             ...monitor,
             locations: [localLoc],
           })
         );
+        expect(result[ConfigKey.SOURCE_PROJECT_CONTENT]).to.be.a('string');
+        expect(await unzipFile(result[ConfigKey.SOURCE_PROJECT_CONTENT])).to.contain(
+          monitor.inline_script
+        );
       });
     });
   });