diff --git a/src/components/ga4/EventBuilder/ValidateEvent/handlers/formatCheckLib.spec.ts b/src/components/ga4/EventBuilder/ValidateEvent/handlers/formatCheckLib.spec.ts
index 0e298d50..cfc367cf 100644
--- a/src/components/ga4/EventBuilder/ValidateEvent/handlers/formatCheckLib.spec.ts
+++ b/src/components/ga4/EventBuilder/ValidateEvent/handlers/formatCheckLib.spec.ts
@@ -2,61 +2,149 @@ import "jest"
 import { formatCheckLib } from "./formatCheckLib" 
 
 describe("formatCheckLib", () => {
-    describe("returns appInstanceIdErrors", () => {
-        test("does not return an error when app_instance_id is 32 alpha-numeric chars", () => {
-            const payload = {app_instance_id: "12345678901234567890123456789012"}
-            const firebaseAppId = '1:1233455666:android:abcdefgh'
-            const api_secret = '123'
-
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
-
-            expect(errors).toEqual([])
+    describe("returns appOrClientErrors", () => {
+        describe("when useFirebase is true", () => {
+            test("does not return an error when app_instance_id is 32 alpha-numeric chars", () => {
+                const payload = {app_instance_id: "12345678901234567890123456789012"}
+                const firebaseAppId = '1:1233455666:android:abcdefgh'
+                const instanceId = {firebase_app_id: firebaseAppId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
+
+                expect(errors).toEqual([])
+            })
+
+            test("returns an error when appInstanceId is not 32 chars", () => {
+                const appInstanceId = "123456789012345678901234567890123"
+                const payload = {app_instance_id: appInstanceId}
+                const firebaseAppId = '1:1233455666:android:abcdefgh'
+                const instanceId = {firebase_app_id: firebaseAppId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
+
+                expect(errors[0].description).toEqual(
+                    `Measurement app_instance_id is expected to be a 32 digit hexadecimal number but was [${ appInstanceId.length }] digits.`
+                )
+            })
+
+            test("returns an error when appInstanceId contains non-alphanumeric char", () => {
+                const appInstanceId = "1234567890123456789012345678901g"
+                const payload = {app_instance_id: appInstanceId}
+                const firebaseAppId = '1:1233455666:android:abcdefgh'
+                const instanceId = {firebase_app_id: firebaseAppId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
+
+                expect(errors[0].description).toEqual(
+                    `Measurement app_instance_id contains non hexadecimal character [g].`,
+                )
+            })
+
+            test("returns an error when appInstanceId is null", () => {
+                const appInstanceId = ""
+                const payload = {app_instance_id: appInstanceId}
+                const firebaseAppId = '1:1233455666:android:abcdefgh'
+                const instanceId = {firebase_app_id: firebaseAppId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
+
+                expect(errors[0].description).toEqual(
+                    "Measurement requires an app_instance_id.",
+                )
+            })
+
+            test("returns an error when appInstanceId not present in the payload", () => {
+                const payload = {}
+                const firebaseAppId = '1:1233455666:android:abcdefgh'
+                const instanceId = {firebase_app_id: firebaseAppId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
+
+                expect(errors[0].description).toEqual(
+                    "Measurement requires an app_instance_id.",
+                )
+            })
         })
 
-        test("returns an error when appInstanceId is not 32 chars", () => {
-            const appInstanceId = "123456789012345678901234567890123"
-            const payload = {app_instance_id: appInstanceId}
-            const firebaseAppId = '1:1233455666:android:abcdefgh'
-            const api_secret = '123'
-
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
-
-            expect(errors[0].description).toEqual(
-                `Measurement app_instance_id is expected to be a 32 digit hexadecimal number but was [${ appInstanceId.length }] digits.`
-            )
-        })
-
-        test("returns an error when appInstanceId contains non-alphanumeric char", () => {
-            const appInstanceId = "1234567890123456789012345678901g"
-            const payload = {app_instance_id: appInstanceId}
-            const firebaseAppId = '1:1233455666:android:abcdefgh'
-            const api_secret = '123'
-
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
-
-            expect(errors[0].description).toEqual(
-                `Measurement app_instance_id contains non hexadecimal character [g].`,
-            )
+        describe("when useFirebase is false", () => {
+            test("does not return an error when client_id is present", () => {
+                const payload = {client_id: "12345678901234567890123456789012"}
+                const measurementId = 'test'
+                const instanceId = {measurement_id: measurementId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, false)
+
+                expect(errors).toEqual([])
+            })
+
+            test("returns an error when client_id is not present", () => {
+                const payload = {}
+                const measurementId = 'test'
+                const instanceId = {measurement_id: measurementId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, false)
+
+                expect(errors[0].description).toEqual(
+                    "Measurement requires a client_id.",
+                )
+            })
+
+            test("returns an error when appInstanceId contains non-alphanumeric char", () => {
+                const appInstanceId = "1234567890123456789012345678901g"
+                const payload = {app_instance_id: appInstanceId}
+                const firebaseAppId = '1:1233455666:android:abcdefgh'
+                const instanceId = {firebase_app_id: firebaseAppId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
+
+                expect(errors[0].description).toEqual(
+                    `Measurement app_instance_id contains non hexadecimal character [g].`,
+                )
+            })
+
+            test("returns an error when appInstanceId is null", () => {
+                const appInstanceId = ""
+                const payload = {app_instance_id: appInstanceId}
+                const firebaseAppId = '1:1233455666:android:abcdefgh'
+                const instanceId = {firebase_app_id: firebaseAppId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
+
+                expect(errors[0].description).toEqual(
+                    "Measurement requires an app_instance_id.",
+                )
+            })
         })
     })
 
     describe("returns invalidEventName errors", () => {
         test("does not return an error for a valid event name", () => {
-            const payload = {events: [{name: 'add_payment_info'}]}
+            const payload = {app_instance_id: "12345678901234567890123456789012", events: [{name: 'add_payment_info'}]}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors).toEqual([])
         })
 
         test("returns an error when event's name is a reserved name", () => {
-            const payload = {events: [{name: 'ad_click'}]}
+            const payload = {app_instance_id: "12345678901234567890123456789012", events: [{name: 'ad_click'}]}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors[0].description).toEqual(
                 "ad_click is a reserved event name"
@@ -66,21 +154,23 @@ describe("formatCheckLib", () => {
 
     describe("returns invalidUserPropertyName errors", () => {
         test("does not return an error for a valid user property name", () => {
-            const payload = {user_properties: {'test': 'test'}}
+            const payload = {app_instance_id: "12345678901234567890123456789012", user_properties: {'test': 'test'}}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors).toEqual([])
         })
 
         test("returns an error when event's name is a reserved name", () => {
-            const payload = {user_properties: {'first_open_time': 'test'}}
+            const payload = {app_instance_id: "12345678901234567890123456789012", user_properties: {'first_open_time': 'test'}}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors[0].description).toEqual(
                 "user_property: 'first_open_time' is a reserved user property name"
@@ -90,21 +180,23 @@ describe("formatCheckLib", () => {
 
     describe("returns invalidCurrencyType errors", () => {
         test("does not return an error for a valid currency type", () => {
-            const payload = {events: [{params: {currency: 'USD'}}]}
+            const payload = {app_instance_id: "12345678901234567890123456789012", events: [{params: {currency: 'USD'}}]}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors).toEqual([])
         })
 
         test("returns an error for an invalid currency type", () => {
-            const payload = {events: [{params: {currency: 'USDD'}}]}
+            const payload = {app_instance_id: "12345678901234567890123456789012", events: [{params: {currency: 'USDD'}}]}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors[0].description).toEqual(
                 "currency: USDD must be a valid uppercase 3-letter ISO 4217 format"
@@ -114,21 +206,23 @@ describe("formatCheckLib", () => {
 
     describe("validates items array", () => {
         test("does not return an error if items array is valid", () => {
-            const payload = {events: [{params: {items: [{'item_id': 1234}]}}]}
+            const payload = {app_instance_id: "12345678901234567890123456789012", events: [{params: {items: [{'item_id': 1234}]}}]}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors).toEqual([])
         })
 
         test("returns an error when items does not have either item_id or item_name", () => {
-            const payload = {events: [{params: {items: [{'item_namee': 'test'}]}}]}
+            const payload = {app_instance_id: "12345678901234567890123456789012", events: [{params: {items: [{'item_namee': 'test'}]}}]}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors[0].description).toEqual(
                 "'items' object must contain one of the following keys: 'item_id' or 'item_name'"
@@ -136,11 +230,12 @@ describe("formatCheckLib", () => {
         })
 
         test("validates empty items array when event requires items", () => {
-            const payload = {events: [{params: {name: 'purchase', items: []}}]}
+            const payload = {app_instance_id: "12345678901234567890123456789012", events: [{params: {name: 'purchase', items: []}}]}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors[0].description).toEqual(
                 "'items' should not be empty; One of 'item_id' or 'item_name' is a required key"
@@ -148,27 +243,30 @@ describe("formatCheckLib", () => {
         })
 
         test("does not validate empty items array when event doesn't require items", () => {
-            const payload = {events: [{params: {name: 'random', items: []}}]}
+            const payload = {app_instance_id: "12345678901234567890123456789012", events: [{params: {name: 'random', items: []}}]}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors).toEqual([])
         })
 
         test("does not validate empty items array when event does not have a name", () => {
-            const payload = {events: [{params: {items: []}}]}
+            const payload = {app_instance_id: "12345678901234567890123456789012", events: [{params: {items: []}}]}
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors).toEqual([])
         })
 
         test("returns an error when item_id and item_name keys have empty values", () => {
             const payload = {
+                app_instance_id: "12345678901234567890123456789012", 
                 events: [
                     {
                         params: {
@@ -183,9 +281,10 @@ describe("formatCheckLib", () => {
                 ] 
             }
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors[0].description).toEqual(
                 "'items' object must contain one of the following keys: 'item_id' or 'item_name'"
@@ -193,47 +292,103 @@ describe("formatCheckLib", () => {
         })
     })
 
-    describe("validates firebase_app_id", () => {
-        test("does not return an error if firebase_app_id is valid", () => {
-            const payload = {}
-            const firebaseAppId = '1:1233455666:android:abcdefgh'
-            const api_secret = '123'
+    describe("validates instance_id", () => {
+        describe("when useFirebase is true", () => {
+            test("does not return an error if firebase_app_id is valid", () => {
+                const payload = {app_instance_id: "12345678901234567890123456789012"}
+                const firebaseAppId = '1:1233455666:android:abcdefgh'
+                const instanceId = {firebase_app_id: firebaseAppId}
+                const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
-            expect(errors).toEqual([])
+                expect(errors).toEqual([])
+            })
+
+            test("returns an error when firebase_app_id is invalid", () => {
+                const payload = {app_instance_id: "12345678901234567890123456789012"}
+                const firebaseAppId = '1233455666:android:abcdefgh'
+                const instanceId = {firebase_app_id: firebaseAppId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
+
+                expect(errors[0].description).toEqual(
+                    `${firebaseAppId} does not follow firebase_app_id pattern of X:XX:XX:XX at path`
+                )
+            })
+
+            test("does not validate measurement_id", () => {
+                const payload = {app_instance_id: "12345678901234567890123456789012"}
+                const firebaseAppId = '1:1233455666:android:abcdefgh'
+                const measurementId = ''
+                const instanceId = {firebase_app_id: firebaseAppId, measurement_id: measurementId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, true)
+
+                expect(errors).toEqual([])
+            })
         })
 
-        test("returns an error when firebase_app_id is invalid", () => {
-            const payload = {}
-            const firebaseAppId = '1233455666:android:abcdefgh'
-            const api_secret = '123'
+        describe("when useFirebase is false", () => {
+            test("does not return an error if measurement_id is not null", () => {
+                const payload = {client_id: "12345678901234567890123456789012"}
+                const measurementId = 'test'
+                const instanceId = {measurement_id: measurementId}
+                const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+                let errors = formatCheckLib(payload, instanceId, api_secret, false)
 
-            expect(errors[0].description).toEqual(
-                `${firebaseAppId} does not follow firebase_app_id pattern of X:XX:XX:XX at path`
-            )
+                expect(errors).toEqual([])
+            })
+
+            test("returns an error when meausrement_id is null", () => {
+                const payload = {client_id: "12345678901234567890123456789012"}
+                const measurementId = ''
+                const instanceId = {measurement_id: measurementId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, false)
+
+                expect(errors[0].description).toEqual(
+                    "Unable to find non-empty parameter [measurement_id] value in request."
+                )
+            })
+
+            test("does not validate firebase_app_id", () => {
+                const payload = {client_id: "12345678901234567890123456789012"}
+                const firebaseAppId = '1233455666:android:abcdefgh'
+                const measurementId = 'test'
+                const instanceId = {firebase_app_id: firebaseAppId, measurement_id: measurementId}
+                const api_secret = '123'
+
+                let errors = formatCheckLib(payload, instanceId, api_secret, false)
+
+                expect(errors).toEqual([])
+            })
         })
     })
 
     describe("validates api_secret", () => {
         test("does not return an error api_secret is not null", () => {
-            const payload = {}
+            const payload = { app_instance_id: "12345678901234567890123456789012" }
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = '123'
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors).toEqual([])
         })
 
         test("returns an error when api_secret is null", () => {
-            const payload = {}
+            const payload = { app_instance_id: "12345678901234567890123456789012" }
             const firebaseAppId = '1:1233455666:android:abcdefgh'
+            const instanceId = {firebase_app_id: firebaseAppId}
             const api_secret = ''
 
-            let errors = formatCheckLib(payload, firebaseAppId, api_secret)
+            let errors = formatCheckLib(payload, instanceId, api_secret, true)
 
             expect(errors[0].description).toEqual(
                 "Unable to find non-empty parameter [api_secret] value in request."
diff --git a/src/components/ga4/EventBuilder/ValidateEvent/handlers/formatCheckLib.ts b/src/components/ga4/EventBuilder/ValidateEvent/handlers/formatCheckLib.ts
index 6400f187..18232d3e 100644
--- a/src/components/ga4/EventBuilder/ValidateEvent/handlers/formatCheckLib.ts
+++ b/src/components/ga4/EventBuilder/ValidateEvent/handlers/formatCheckLib.ts
@@ -18,55 +18,72 @@ const RESERVED_USER_PROPERTY_NAMES = [
 
 // formatCheckLib provides additional validations for payload not included in 
 // the schema validations. All checks are consistent with Firebase documentation.
-export const formatCheckLib = (payload, firebaseAppId, api_secret) => {
+export const formatCheckLib = (payload, instanceId, api_secret, useFirebase) => {
     let errors: ValidationMessage[] = []
 
-    const appInstanceIdErrors = isValidAppInstanceId(payload)
+    const appOrClientErrors = isValidAppOrClientId(payload, useFirebase)
     const eventNameErrors = isValidEventName(payload)
     const userPropertyNameErrors = isValidUserPropertyName(payload)
     const currencyErrors = isValidCurrencyType(payload)
     const emptyItemsErrors = isItemsEmpty(payload)
     const itemsRequiredKeyErrors = itemsHaveRequiredKey(payload)
-    const firebaseAppIdErrors = isfirebaseAppIdValid(firebaseAppId)
+    const instanceIdErrors = isInstanceIdValid(instanceId, useFirebase)
     const apiSecretErrors = isApiSecretNotNull(api_secret)
     const sizeErrors = isTooBig(payload)
 
     return [
         ...errors, 
-        ...appInstanceIdErrors, 
+        ...appOrClientErrors, 
         ...eventNameErrors,
         ...userPropertyNameErrors,
         ...currencyErrors,
         ...emptyItemsErrors,
         ...itemsRequiredKeyErrors,
-        ...firebaseAppIdErrors,
+        ...instanceIdErrors,
         ...apiSecretErrors,
         ...sizeErrors,
     ]
 }
 
-const isValidAppInstanceId = (payload) => {
+const isValidAppOrClientId = (payload, useFirebase) => {
     let errors: ValidationMessage[] = []
     const appInstanceId = payload.app_instance_id
+    const clientId = payload.client_id
 
-    if (appInstanceId) {
-        if (appInstanceId?.length !== 32) {
+    if (useFirebase) {
+        if (appInstanceId) {
+            if (appInstanceId?.length !== 32) {
+                errors.push({
+                    description: `Measurement app_instance_id is expected to be a 32 digit hexadecimal number but was [${appInstanceId.length}] digits.`,
+                    validationCode: "value_invalid",
+                    fieldPath: "app_instance_id"
+                })
+            }
+
+            if (!appInstanceId.match(/^[A-Fa-f0-9]+$/)) {
+                let nonChars = appInstanceId.split('').filter((letter: string)=> {
+                    return (!/[0-9A-Fa-f]/.test(letter))
+                })
+
+                errors.push({
+                    description: `Measurement app_instance_id contains non hexadecimal character [${nonChars[0]}].`,
+                    validationCode: "value_invalid",
+                    fieldPath: "app_instance_id"
+                })
+            }
+        } else {
             errors.push({
-                description: `Measurement app_instance_id is expected to be a 32 digit hexadecimal number but was [${appInstanceId.length}] digits.`,
+                description: "Measurement requires an app_instance_id.",
                 validationCode: "value_invalid",
                 fieldPath: "app_instance_id"
             })
         }
-
-        if (!appInstanceId.match(/^[A-Fa-f0-9]+$/)) {
-            let nonChars = appInstanceId.split('').filter((letter: string)=> {
-                return (!/[0-9A-Fa-f]/.test(letter))
-            })
-
+    } else {
+        if (!clientId) {
             errors.push({
-                description: `Measurement app_instance_id contains non hexadecimal character [${nonChars[0]}].`,
+                description: "Measurement requires a client_id.",
                 validationCode: "value_invalid",
-                fieldPath: "app_instance_id"
+                fieldPath: "client_id"
             })
         }
     }
@@ -182,15 +199,27 @@ const requiredKeysEmpty = (itemsObj) => {
     return !(itemsObj.item_id || itemsObj.item_name)
 }
 
-const isfirebaseAppIdValid = (firebaseAppId) => {
+const isInstanceIdValid = (instanceId, useFirebase) => {
     let errors: ValidationMessage[] = []
+    const firebaseAppId = instanceId?.firebase_app_id
+    const measurementId = instanceId?.measurement_id
 
-    if (firebaseAppId && !firebaseAppId.match(/[0-9]:[0-9]+:[a-zA-Z]+:[a-zA-Z0-9]+$/)) {
-        errors.push({
-            description: `${firebaseAppId} does not follow firebase_app_id pattern of X:XX:XX:XX at path`,
-            validationCode: "value_invalid",
-            fieldPath: "firebase_app_id"
-        })
+    if (useFirebase) {
+        if (firebaseAppId && !firebaseAppId.match(/[0-9]:[0-9]+:[a-zA-Z]+:[a-zA-Z0-9]+$/)) {
+            errors.push({
+                description: `${firebaseAppId} does not follow firebase_app_id pattern of X:XX:XX:XX at path`,
+                validationCode: "value_invalid",
+                fieldPath: "firebase_app_id"
+            })
+        }
+    } else {
+        if (!measurementId) {
+            errors.push({
+                description: "Unable to find non-empty parameter [measurement_id] value in request.",
+                validationCode: "value_invalid",
+                fieldPath: "measurement_id"
+            })
+        }
     }
 
     return errors
diff --git a/src/components/ga4/EventBuilder/ValidateEvent/handlers/responseUtil.ts b/src/components/ga4/EventBuilder/ValidateEvent/handlers/responseUtil.ts
index e233d339..4e5d713e 100644
--- a/src/components/ga4/EventBuilder/ValidateEvent/handlers/responseUtil.ts
+++ b/src/components/ga4/EventBuilder/ValidateEvent/handlers/responseUtil.ts
@@ -9,11 +9,12 @@ const API_DOC_EVENT_URL = 'https://developers.google.com/analytics/devguides/col
 const API_DOC_USER_PROPERTIES = 'https://developers.google.com/analytics/devguides/collection/protocol/ga4/user-properties?hl=en&client_type=firebase'
 const API_DOC_SENDING_EVENTS_URL = 'https://developers.google.com/analytics/devguides/collection/protocol/ga4/sending-events?hl=en&client_type=firebase'
 const API_DOC_JSON_POST_BODY = 'https://developers.google.com/analytics/devguides/collection/protocol/ga4/reference?hl=en&client_type=firebase#payload_post_body'
+const API_DOC_GTAG = 'https://developers.google.com/analytics/devguides/collection/protocol/ga4/sending-events?client_type=gtag#required_parameters'
 
 const BASE_PAYLOAD_ATTRIBUTES = ['app_instance_id', 'api_secret', 'firebase_app_id', 'user_id', 'timestamp_micros', 'user_properties', 'non_personalized_ads']
 
 // formats error messages for clarity; add documentation to each error
-export const formatErrorMessages = (errors, payload) => {
+export const formatErrorMessages = (errors, payload, useFirebase) => {
     const formattedErrors = errors.map(error => {
         const { description, fieldPath } = error
 
@@ -28,6 +29,7 @@ export const formatErrorMessages = (errors, payload) => {
             error['description'] = description.slice(0, end_index) + ALPHA_NUMERIC_OVERRIDE
 
             return error
+        
         } else if (BASE_PAYLOAD_ATTRIBUTES.includes(fieldPath?.slice(2))) {
             error['fieldPath'] = fieldPath.slice(2)
 
@@ -39,20 +41,22 @@ export const formatErrorMessages = (errors, payload) => {
     })
 
     const documentedErrors = formattedErrors.map(error => {
-        error['documentation'] = addDocumentation(error, payload)
+        error['documentation'] = addDocumentation(error, payload, useFirebase)
         return error
     })
 
     return documentedErrors
 }
 
-const addDocumentation = (error, payload) => {
+const addDocumentation = (error, payload, useFirebase) => {
     const { fieldPath, validationCode } = error
 
     if (validationCode === 'max-length-error' || validationCode === 'max-properties-error' || validationCode === 'max-body-size') {
         return API_DOC_LIMITATIONS_URL
     } else if (fieldPath?.startsWith('#/events/')) {
         return API_DOC_EVENT_URL + payload?.events[0]?.name
+    } else if (!useFirebase && (fieldPath === 'client_id' || fieldPath === 'measurement_id')) {
+        return API_DOC_GTAG
     } else if (BASE_PAYLOAD_ATTRIBUTES.includes(fieldPath)) {
         return API_DOC_BASE_PAYLOAD_URL + fieldPath
     } else if (fieldPath === '#/user_properties') {
diff --git a/src/components/ga4/EventBuilder/ValidateEvent/schemas/baseContent.spec.ts b/src/components/ga4/EventBuilder/ValidateEvent/schemas/baseContent.spec.ts
index 69159539..2456ece2 100644
--- a/src/components/ga4/EventBuilder/ValidateEvent/schemas/baseContent.spec.ts
+++ b/src/components/ga4/EventBuilder/ValidateEvent/schemas/baseContent.spec.ts
@@ -1,4 +1,6 @@
 import "jest"
+import { invalid } from "moment"
+import { ValidationStatus } from "../../types"
 import { Validator } from "../validator"
 import { baseContentSchema } from "./baseContent" 
 
@@ -17,10 +19,14 @@ describe("baseContentSchema", () => {
         expect(validator.isValid(validInput)).toEqual(true)
     })
 
-    test("is not valid when an app_instance_id has dashes", () => {
+    test("is not valid with an additional property", () => {
         const invalidInput = {
-            'app_instance_id': '0239500a-23af-4ab0-a79c-58c4042ea175',
-            'events': []
+            'app_instance_id': 'bc17b822c8c84a7e84ac7e010cc2f740',
+            'events': [{
+                'name': 'something',
+                'params': {}
+            }],
+            'additionalProperty': 123
         }
 
         let validator = new Validator(baseContentSchema)
@@ -28,34 +34,114 @@ describe("baseContentSchema", () => {
         expect(validator.isValid(invalidInput)).toEqual(false)
     })
 
-    test("is not valid when an app_instance_id is not 32 chars", () => {
-        const invalidInput = {
-            'app_instance_id': 'bc17b822c8c84a7e84ac7e010cc2f74',
-            'events': []
+    test("validates specific event names", () => {
+        const validInput = {
+            'app_instance_id': 'bc17b822c8c84a7e84ac7e010cc2f740',
+            'events': [{
+                'name': 'purchase',
+                'params': {
+                    'transaction_id': '894982',
+                    'value': 89489,
+                    'currency': 'USD',
+                    'items': [
+                        {
+                            'item_name': 'test'
+                        }
+                    ]
+                }
+            }],
         }
 
         let validator = new Validator(baseContentSchema)
 
-        expect(validator.isValid(invalidInput)).toEqual(false)
+        expect(validator.isValid(validInput)).toEqual(true)
     })
 
-    test("is not valid with an additional property", () => {
-        const invalidInput = {
+    test("validates params don't have reserved suffixes", () => {
+        const validInput = {
             'app_instance_id': 'bc17b822c8c84a7e84ac7e010cc2f740',
-            'events': [],
-            'additionalProperty': 123
+            'events': [{
+                'name': 'purchase',
+                'params': {
+                    'transaction_id': '894982',
+                    'value': 89489,
+                    'currency': 'USD',
+                    'ga_test': '123',
+                    'items': [
+                        {
+                            'item_name': 'test'
+                        }
+                    ]
+                }
+            }],
         }
 
         let validator = new Validator(baseContentSchema)
 
-        expect(validator.isValid(invalidInput)).toEqual(false)
+        expect(validator.isValid(validInput)).toEqual(false)
+    })
+
+    test("validates required keys are present for certain events", () => {
+        const validInput = {
+            'app_instance_id': 'bc17b822c8c84a7e84ac7e010cc2f740',
+            'events': [{
+                'name': 'purchase',
+                'params': {
+                    'transaction_id': '894982',
+                    'currency': 'USD',
+                    'items': [
+                        {
+                            'item_name': 'test'
+                        }
+                    ]
+                }
+            }],
+        }
+
+        let validator = new Validator(baseContentSchema)
+
+        expect(validator.isValid(validInput)).toEqual(false)
     })
 
-    test("is not valid without app_instance_id", () => {
-        const invalidInput = {'events': []}
+    test("does NOT validate empty item aray for named events, because the error message is too complex and this is validated in formatCheckErrors", () => {
+        const validInput = {
+            'app_instance_id': 'bc17b822c8c84a7e84ac7e010cc2f740',
+            'events': [{
+                'name': 'purchase',
+                'params': {
+                    'transaction_id': '894982',
+                    'value': 89489,
+                    'currency': 'USD',
+                    'items': [{}]
+                }
+            }],
+        }
 
         let validator = new Validator(baseContentSchema)
 
-        expect(validator.isValid(invalidInput)).toEqual(false)
+        expect(validator.isValid(validInput)).toEqual(true)
+    })
+
+    test("validates that items don't have reserved name keys", () => {
+        const validInput = {
+            'app_instance_id': 'bc17b822c8c84a7e84ac7e010cc2f740',
+            'events': [{
+                'name': 'purchase',
+                'params': {
+                    'transaction_id': '894982',
+                    'value': 89489,
+                    'currency': 'USD',
+                    'items': [
+                        {
+                            'ga_test': 'et'
+                        }
+                    ]
+                }
+            }],
+        }
+
+        let validator = new Validator(baseContentSchema)
+
+        expect(validator.isValid(validInput)).toEqual(false)
     })
 })
\ No newline at end of file
diff --git a/src/components/ga4/EventBuilder/ValidateEvent/schemas/baseContent.ts b/src/components/ga4/EventBuilder/ValidateEvent/schemas/baseContent.ts
index 6a98b5f2..303834fb 100644
--- a/src/components/ga4/EventBuilder/ValidateEvent/schemas/baseContent.ts
+++ b/src/components/ga4/EventBuilder/ValidateEvent/schemas/baseContent.ts
@@ -1,18 +1,20 @@
 // Base JSON Body Content Schema.
 
-// from google3.corp.gtech.ads.infrastructure.mapps_s2s_event_validator.schemas import events
 import { userPropertiesSchema } from './userProperties'
 import { eventsSchema } from './events'
 
 export const baseContentSchema = {
     "type": "object",
-    "required": ["app_instance_id", "events"],
+    "required": ["events"],
     "additionalProperties": false,
     "properties": {
         "app_instance_id": {
             "type": "string",
             "format": "app_instance_id"
         },
+        "client_id": {
+            "type": "string",
+        },
         "user_id": {
             "type": "string"
         },
@@ -25,4 +27,4 @@ export const baseContentSchema = {
         },
         "events": eventsSchema,
     }
-}
+}
\ No newline at end of file
diff --git a/src/components/ga4/EventBuilder/ValidateEvent/schemas/event.ts b/src/components/ga4/EventBuilder/ValidateEvent/schemas/event.ts
index df35c9e2..db7876ac 100644
--- a/src/components/ga4/EventBuilder/ValidateEvent/schemas/event.ts
+++ b/src/components/ga4/EventBuilder/ValidateEvent/schemas/event.ts
@@ -1,4 +1,5 @@
 import { buildEvents } from "./schemaBuilder"
+import { itemsSchema } from "./eventTypes/items"
 
 export const eventSchema = {
     "type": "object",
@@ -12,7 +13,8 @@ export const eventSchema = {
             "pattern": "^[A-Za-z][A-Za-z0-9_]*$",
             "maxLength": 40
         },
-        "params": {"type": "object"}
+        "params": {"type": "object"},
+        "items": itemsSchema
     },
     "allOf": buildEvents()
 }
diff --git a/src/components/ga4/EventBuilder/ValidateEvent/schemas/eventTypes/item.ts b/src/components/ga4/EventBuilder/ValidateEvent/schemas/eventTypes/item.ts
index 1972f3d7..28acca19 100644
--- a/src/components/ga4/EventBuilder/ValidateEvent/schemas/eventTypes/item.ts
+++ b/src/components/ga4/EventBuilder/ValidateEvent/schemas/eventTypes/item.ts
@@ -5,14 +5,15 @@ import { ITEM_FIELDS } from "./fieldDefinitions"
 
 export const itemSchema = {
     "type": "object",
-    "required": [],
     "patternProperties": {
         ".": {
             "maxLength": 100
         }
     },
     "propertyNames": {
-        "maxLength": 40
+        "maxLength": 40,
+        "pattern":
+            "^(?!ga_|google_|firebase_)[A-Za-z][A-Za-z0-9_]*$",
     },
     "properties": ITEM_FIELDS,
     "anyOf": [{
diff --git a/src/components/ga4/EventBuilder/ValidateEvent/useValidateEvent.ts b/src/components/ga4/EventBuilder/ValidateEvent/useValidateEvent.ts
index 48ae3f92..b33d785c 100644
--- a/src/components/ga4/EventBuilder/ValidateEvent/useValidateEvent.ts
+++ b/src/components/ga4/EventBuilder/ValidateEvent/useValidateEvent.ts
@@ -131,8 +131,9 @@ const useValidateEvent = (): Requestable<
     let validator = new Validator(baseContentSchema)
     let formatCheckErrors: ValidationMessage[] | [] = formatCheckLib(
       payload, 
-      instanceId?.firebase_app_id,
-      api_secret
+      instanceId,
+      api_secret,
+      useFirebase
     )
 
     if (!validator.isValid(payload) || formatCheckErrors) {
@@ -158,7 +159,7 @@ const useValidateEvent = (): Requestable<
     setValidationMessages([])
 
     if (!useTextBox || Object.keys(payload).length !== 0) {
-      let validatorErrors = useFirebase ? validatePayloadAttributes(payload) : []
+      let validatorErrors = validatePayloadAttributes(payload)
 
       validateHit(payload, instanceId, api_secret)
         .then(messages => {
@@ -171,14 +172,14 @@ const useValidateEvent = (): Requestable<
                     ? useFirebase
                     : true
                 )
-              
+
               apiValidationErrors.forEach(err => {
                 if (!validatorErrors.map(e => e.description).includes(err.description)) {
                   validatorErrors.push(err)
                 }
               })
 
-              validatorErrors = formatErrorMessages(validatorErrors, payload)
+              validatorErrors = formatErrorMessages(validatorErrors, payload, useFirebase)
               
               setValidationMessages(validatorErrors)
               setStatus(RequestStatus.Failed)
diff --git a/src/components/ga4/EventBuilder/index.tsx b/src/components/ga4/EventBuilder/index.tsx
index 24880fff..ed520c36 100644
--- a/src/components/ga4/EventBuilder/index.tsx
+++ b/src/components/ga4/EventBuilder/index.tsx
@@ -252,6 +252,10 @@ const EventBuilder: React.FC = () => {
               checked={useFirebase}
               onChange={e => {
                 setUseFirebase(e.target.checked)
+
+                if (!e.target.checked) {
+                  setUseTextBox(false)
+                }
               }}
               name="use firebase"
               color="primary"