diff --git a/src/factory/BackendFactory.ts b/src/factory/BackendFactory.ts
index a41d714..9e0c51d 100644
--- a/src/factory/BackendFactory.ts
+++ b/src/factory/BackendFactory.ts
@@ -67,7 +67,7 @@ export class BackendFactory {
      * @returns {@link BackendService}
      */
     public static getCustomRPCService(baseUrl: string): BackendService {
-        return new BackendServiceImpl(baseUrl);
+        return BackendServiceImpl.byBaseUrl(baseUrl);
     }
 }
 
diff --git a/src/factory/BackendService.ts b/src/factory/BackendService.ts
index 4625a96..3ef5156 100644
--- a/src/factory/BackendService.ts
+++ b/src/factory/BackendService.ts
@@ -12,6 +12,13 @@ import { AccountService } from '../api/account/AccountService';
  * Backend Service
  */
 export interface BackendService {
+
+    /**
+     * Get Base URL
+     * @return string - base url
+     */
+    getBaseUrl(): string;
+
     /**
      * Get Network Service
      *
diff --git a/src/factory/impl/BackendServiceImpl.ts b/src/factory/impl/BackendServiceImpl.ts
index 41bf914..29eaded 100644
--- a/src/factory/impl/BackendServiceImpl.ts
+++ b/src/factory/impl/BackendServiceImpl.ts
@@ -26,6 +26,7 @@ import { OperationType } from "@app/factory/OperationType";
  */
 export class BackendServiceImpl implements BackendService {
 
+    private readonly baseUrl: string;
     private readonly networkService: NetworkService;
     private readonly epochService: EpochService;
     private readonly blockService: BlockService;
@@ -50,6 +51,7 @@ export class BackendServiceImpl implements BackendService {
      */
     constructor(baseUrl: string) {
         console.log(`Koios URL: ${baseUrl}`);
+        this.baseUrl = baseUrl;
         this.networkService = new NetworkServiceImpl(baseUrl);
         this.epochService = new EpochServiceImpl(baseUrl);
         this.blockService = new BlockServiceImpl(baseUrl);
@@ -61,6 +63,10 @@ export class BackendServiceImpl implements BackendService {
         this.accountService = new AccountServiceImpl(baseUrl);
     }
 
+    getBaseUrl(): string {
+        return this.baseUrl
+    }
+
     getNetworkService(): NetworkService {
         return this.networkService;
     }
diff --git a/tests/PreviewService.test.ts b/tests/PreviewService.test.ts
index 1780d6e..7eb46ad 100644
--- a/tests/PreviewService.test.ts
+++ b/tests/PreviewService.test.ts
@@ -31,6 +31,10 @@ describe("koiosBeckendService", () => {
         const koiosMainnetService = BackendFactory.getKoiosMainnetService()
         expect(koiosMainnetService).toBeInstanceOf(BackendServiceImpl)
     })
+    test("koiosCustomRPCService", () => {
+        const koiosCustomRPCService = BackendFactory.getCustomRPCService("https://preview.koios.rest/api/v0/")
+        expect(koiosPreviewService.getBaseUrl()).toBe(koiosCustomRPCService.getBaseUrl())
+    })
     test("koiosMainnetServiceByApiVersion", () => {
         const koiosMainnetService = BackendFactory.getKoiosMainnetService(ApiVersion.VERSION_0)
         expect(koiosMainnetService).toBeInstanceOf(BackendServiceImpl)
@@ -181,8 +185,10 @@ describe("koiosTransactionsService", () => {
         const result = await koiosTransactionsService.submitTransaction(new Uint8Array([0]))
         console.log(result)
         expect(result).toBeInstanceOf(KoiosHttpError)
-        expect(result.statusCode).toBe(400)
-        expect(result.statusText).toBe('Bad Request')
+        const koiosHttpError: KoiosHttpError = result
+        expect(koiosHttpError.getStatusCode()).toBe(400)
+        expect(koiosHttpError.getStatusText()).toBe('Bad Request')
+        expect(koiosHttpError.getUrl()).not.toBeNull()
     });
     test("getTransactionStatus", async () => {
         const txHashes = [