diff --git a/backend/eslint.config.mjs b/backend/eslint.config.mjs
index 7ea3ba9..8388bcf 100644
--- a/backend/eslint.config.mjs
+++ b/backend/eslint.config.mjs
@@ -43,4 +43,10 @@ export default tseslint.config(
       }],
     },
   },
+  {
+    files: ['**/*.spec.ts', '**/*.test.ts'],
+    rules: {
+      '@typescript-eslint/unbound-method': 'off',
+    },
+  },
 );
diff --git a/backend/package-lock.json b/backend/package-lock.json
index d083cea..65e3e05 100644
--- a/backend/package-lock.json
+++ b/backend/package-lock.json
@@ -11,16 +11,19 @@
       "license": "MIT",
       "dependencies": {
         "@invoisio/soroban-client": "file:../soroban/client",
+        "@nestjs/axios": "^4.0.1",
         "@nestjs/common": "^11.0.1",
         "@nestjs/config": "^4.0.2",
         "@nestjs/core": "^11.0.1",
         "@nestjs/jwt": "^11.0.2",
         "@nestjs/passport": "^11.0.5",
         "@nestjs/platform-express": "^11.0.1",
+        "@nestjs/schedule": "^6.1.1",
         "@nestjs/typeorm": "^11.0.0",
         "@prisma/adapter-pg": "^7.4.2",
         "@prisma/client": "^7.4.2",
         "@stellar/stellar-sdk": "^14.6.0",
+        "axios": "^1.13.6",
         "class-transformer": "^0.5.1",
         "class-validator": "^0.14.2",
         "cross-env": "^10.1.0",
@@ -2272,6 +2275,17 @@
         "@tybys/wasm-util": "^0.10.0"
       }
     },
+    "node_modules/@nestjs/axios": {
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/@nestjs/axios/-/axios-4.0.1.tgz",
+      "integrity": "sha512-68pFJgu+/AZbWkGu65Z3r55bTsCPlgyKaV4BSG8yUAD72q1PPuyVRgUwFv6BxdnibTUHlyxm06FmYWNC+bjN7A==",
+      "license": "MIT",
+      "peerDependencies": {
+        "@nestjs/common": "^10.0.0 || ^11.0.0",
+        "axios": "^1.3.1",
+        "rxjs": "^7.0.0"
+      }
+    },
     "node_modules/@nestjs/cli": {
       "version": "11.0.16",
       "resolved": "https://registry.npmjs.org/@nestjs/cli/-/cli-11.0.16.tgz",
@@ -2509,6 +2523,19 @@
         "@nestjs/core": "^11.0.0"
       }
     },
+    "node_modules/@nestjs/schedule": {
+      "version": "6.1.1",
+      "resolved": "https://registry.npmjs.org/@nestjs/schedule/-/schedule-6.1.1.tgz",
+      "integrity": "sha512-kQl1RRgi02GJ0uaUGCrXHCcwISsCsJDciCKe38ykJZgnAeeoeVWs8luWtBo4AqAAXm4nS5K8RlV0smHUJ4+2FA==",
+      "license": "MIT",
+      "dependencies": {
+        "cron": "4.4.0"
+      },
+      "peerDependencies": {
+        "@nestjs/common": "^10.0.0 || ^11.0.0",
+        "@nestjs/core": "^10.0.0 || ^11.0.0"
+      }
+    },
     "node_modules/@nestjs/schematics": {
       "version": "11.0.9",
       "resolved": "https://registry.npmjs.org/@nestjs/schematics/-/schematics-11.0.9.tgz",
@@ -3355,6 +3382,12 @@
         "@types/node": "*"
       }
     },
+    "node_modules/@types/luxon": {
+      "version": "3.7.1",
+      "resolved": "https://registry.npmjs.org/@types/luxon/-/luxon-3.7.1.tgz",
+      "integrity": "sha512-H3iskjFIAn5SlJU7OuxUmTEpebK6TKB8rxZShDslBMZJ5u9S//KM1sbdAisiSrqwLQncVjnpi2OK2J51h+4lsg==",
+      "license": "MIT"
+    },
     "node_modules/@types/methods": {
       "version": "1.1.4",
       "resolved": "https://registry.npmjs.org/@types/methods/-/methods-1.1.4.tgz",
@@ -5708,6 +5741,23 @@
       "devOptional": true,
       "license": "MIT"
     },
+    "node_modules/cron": {
+      "version": "4.4.0",
+      "resolved": "https://registry.npmjs.org/cron/-/cron-4.4.0.tgz",
+      "integrity": "sha512-fkdfq+b+AHI4cKdhZlppHveI/mgz2qpiYxcm+t5E5TsxX7QrLS1VE0+7GENEk9z0EeGPcpSciGv6ez24duWhwQ==",
+      "license": "MIT",
+      "dependencies": {
+        "@types/luxon": "~3.7.0",
+        "luxon": "~3.7.0"
+      },
+      "engines": {
+        "node": ">=18.x"
+      },
+      "funding": {
+        "type": "ko-fi",
+        "url": "https://ko-fi.com/intcreator"
+      }
+    },
     "node_modules/cross-env": {
       "version": "10.1.0",
       "resolved": "https://registry.npmjs.org/cross-env/-/cross-env-10.1.0.tgz",
@@ -9212,6 +9262,15 @@
         "url": "https://github.com/sponsors/wellwelwel"
       }
     },
+    "node_modules/luxon": {
+      "version": "3.7.2",
+      "resolved": "https://registry.npmjs.org/luxon/-/luxon-3.7.2.tgz",
+      "integrity": "sha512-vtEhXh/gNjI9Yg1u4jX/0YVPMvxzHuGgCm6tC5kZyb08yjGWGnqAjGJvcXbqQR2P3MyMEFnRbpcdFS6PBcLqew==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=12"
+      }
+    },
     "node_modules/magic-string": {
       "version": "0.30.17",
       "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.30.17.tgz",
diff --git a/backend/package.json b/backend/package.json
index cd50bb7..b0781d6 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -32,16 +32,19 @@
   },
   "dependencies": {
     "@invoisio/soroban-client": "file:../soroban/client",
+    "@nestjs/axios": "^4.0.1",
     "@nestjs/common": "^11.0.1",
     "@nestjs/config": "^4.0.2",
     "@nestjs/core": "^11.0.1",
     "@nestjs/jwt": "^11.0.2",
     "@nestjs/passport": "^11.0.5",
     "@nestjs/platform-express": "^11.0.1",
+    "@nestjs/schedule": "^6.1.1",
     "@nestjs/typeorm": "^11.0.0",
     "@prisma/adapter-pg": "^7.4.2",
     "@prisma/client": "^7.4.2",
     "@stellar/stellar-sdk": "^14.6.0",
+    "axios": "^1.13.6",
     "class-transformer": "^0.5.1",
     "class-validator": "^0.14.2",
     "cross-env": "^10.1.0",
@@ -115,4 +118,4 @@
     "coverageDirectory": "../coverage",
     "testEnvironment": "node"
   }
-}
\ No newline at end of file
+}
diff --git a/backend/prisma/migrations/20260307171500_add_webhooks/migration.sql b/backend/prisma/migrations/20260307171500_add_webhooks/migration.sql
new file mode 100644
index 0000000..b5eab13
--- /dev/null
+++ b/backend/prisma/migrations/20260307171500_add_webhooks/migration.sql
@@ -0,0 +1,29 @@
+-- CreateEnum
+CREATE TYPE "DeliveryStatus" AS ENUM ('pending', 'success', 'failed');
+
+-- AlterTable
+ALTER TABLE "users" ADD COLUMN     "webhook_url" TEXT,
+ADD COLUMN     "webhook_secret" TEXT;
+
+-- CreateTable
+CREATE TABLE "webhook_deliveries" (
+    "id" TEXT NOT NULL,
+    "invoice_id" TEXT NOT NULL,
+    "user_id" TEXT NOT NULL,
+    "url" TEXT NOT NULL,
+    "payload" JSONB NOT NULL,
+    "status" "DeliveryStatus" NOT NULL DEFAULT 'pending',
+    "attempts" INTEGER NOT NULL DEFAULT 0,
+    "last_attempt_at" TIMESTAMP(3),
+    "next_attempt_at" TIMESTAMP(3),
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "webhook_deliveries_pkey" PRIMARY KEY ("id")
+);
+
+-- AddForeignKey
+ALTER TABLE "webhook_deliveries" ADD CONSTRAINT "webhook_deliveries_invoice_id_fkey" FOREIGN KEY ("invoice_id") REFERENCES "invoices"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "webhook_deliveries" ADD CONSTRAINT "webhook_deliveries_user_id_fkey" FOREIGN KEY ("user_id") REFERENCES "users"("id") ON DELETE CASCADE ON UPDATE CASCADE;
diff --git a/backend/prisma/schema.prisma b/backend/prisma/schema.prisma
index 88a9771..0d3da91 100644
--- a/backend/prisma/schema.prisma
+++ b/backend/prisma/schema.prisma
@@ -20,11 +20,39 @@ model User {
   createdAt      DateTime  @default(now())
   updatedAt      DateTime  @updatedAt
 
+  webhookUrl     String?   @map("webhook_url")
+  webhookSecret  String?   @map("webhook_secret")
+
   invoices Invoice[]
+  webhooks WebhookDelivery[]
 
   @@map("users")
 }
 
+model WebhookDelivery {
+  id             String         @id @default(uuid())
+  invoiceId      String         @map("invoice_id")
+  invoice        Invoice        @relation(fields: [invoiceId], references: [id], onDelete: Cascade)
+  userId         String         @map("user_id")
+  user           User           @relation(fields: [userId], references: [id], onDelete: Cascade)
+  url            String
+  payload        Json
+  status         DeliveryStatus @default(pending)
+  attempts       Int            @default(0)
+  lastAttemptAt  DateTime?      @map("last_attempt_at")
+  nextAttemptAt  DateTime?      @map("next_attempt_at")
+  createdAt      DateTime       @default(now()) @map("created_at")
+  updatedAt      DateTime       @updatedAt @map("updated_at")
+
+  @@map("webhook_deliveries")
+}
+
+enum DeliveryStatus {
+  pending
+  success
+  failed
+}
+
 // Invoice model matching backend/src/invoices/entities/invoice.entity.ts
 model Invoice {
   id                 String        @id @default(uuid())
@@ -49,6 +77,8 @@ model Invoice {
   createdAt          DateTime      @default(now()) @map("created_at")
   updatedAt          DateTime      @updatedAt @map("updated_at")
 
+  webhooks           WebhookDelivery[]
+
   @@map("invoices")
 }
 
diff --git a/backend/src/app.module.ts b/backend/src/app.module.ts
index 379a2e0..2ca86b0 100644
--- a/backend/src/app.module.ts
+++ b/backend/src/app.module.ts
@@ -14,6 +14,8 @@ import { HorizonWatcherModule } from "./stellar/horizon-watcher.module";
 import { AuthModule } from "./auth/auth.module";
 import { UsersModule } from "./users/user.module";
 import { PrismaModule } from "./prisma/prisma.module";
+import { ScheduleModule } from "@nestjs/schedule";
+import { WebhooksModule } from "./webhooks/webhooks.module";
 
 /**
  * Root application module
@@ -51,12 +53,14 @@ import { PrismaModule } from "./prisma/prisma.module";
       }),
     }),
     PrismaModule,
+    ScheduleModule.forRoot(),
     HealthModule,
     InvoicesModule,
     StellarModule,
     HorizonWatcherModule,
     AuthModule,
     UsersModule,
+    WebhooksModule,
   ],
 })
 export class AppModule {}
diff --git a/backend/src/invoices/invoices.module.ts b/backend/src/invoices/invoices.module.ts
index 0bbf962..fb6e8e5 100644
--- a/backend/src/invoices/invoices.module.ts
+++ b/backend/src/invoices/invoices.module.ts
@@ -7,6 +7,7 @@ import { StellarModule } from "../stellar/stellar.module";
 import { SorobanModule } from "../soroban/soroban.module";
 import { AuthGuard } from "../auth/auth.guard";
 import { PrismaModule } from "../prisma/prisma.module";
+import { WebhooksModule } from "../webhooks/webhooks.module";
 
 /**
  * Invoices module
@@ -17,6 +18,7 @@ import { PrismaModule } from "../prisma/prisma.module";
     StellarModule,
     SorobanModule,
     PrismaModule,
+    WebhooksModule,
     JwtModule.registerAsync({
       imports: [ConfigModule],
       inject: [ConfigService],
diff --git a/backend/src/invoices/invoices.service.spec.ts b/backend/src/invoices/invoices.service.spec.ts
index 7e99b3b..f262798 100644
--- a/backend/src/invoices/invoices.service.spec.ts
+++ b/backend/src/invoices/invoices.service.spec.ts
@@ -7,6 +7,7 @@ import { CreateInvoiceDto } from "./dto/create-invoice.dto";
 import { validate } from "class-validator";
 import { plainToInstance } from "class-transformer";
 import { PrismaService } from "../prisma/prisma.service";
+import { WebhooksService } from "../webhooks/webhooks.service";
 
 describe("InvoicesService", () => {
   let service: InvoicesService;
@@ -195,6 +196,10 @@ describe("InvoicesService", () => {
     };
   };
 
+  const mockWebhooksService = {
+    enqueueWebhook: jest.fn().mockResolvedValue(undefined),
+  };
+
   beforeEach(async () => {
     const module: TestingModule = await Test.createTestingModule({
       providers: [
@@ -203,6 +208,7 @@ describe("InvoicesService", () => {
         { provide: StellarService, useValue: mockStellarService },
         { provide: SorobanService, useValue: mockSorobanService },
         { provide: PrismaService, useFactory: mockPrisma },
+        { provide: WebhooksService, useValue: mockWebhooksService },
       ],
     }).compile();
 
diff --git a/backend/src/invoices/invoices.service.ts b/backend/src/invoices/invoices.service.ts
index 1807a98..f447024 100644
--- a/backend/src/invoices/invoices.service.ts
+++ b/backend/src/invoices/invoices.service.ts
@@ -11,6 +11,7 @@ import { StellarService } from "../stellar/stellar.service";
 import { SorobanService } from "../soroban/soroban.service";
 import { PrismaService } from "../prisma/prisma.service";
 import { Prisma, InvoiceStatus } from "@prisma/client";
+import { WebhooksService } from "../webhooks/webhooks.service";
 
 /**
  * Invoices service — manages invoice lifecycle and Soroban on-chain settlement.
@@ -24,6 +25,7 @@ export class InvoicesService implements OnModuleInit {
     private readonly stellarService: StellarService,
     private readonly sorobanService: SorobanService,
     private readonly prisma: PrismaService,
+    private readonly webhooksService: WebhooksService,
   ) {}
 
   async onModuleInit() {
@@ -122,6 +124,10 @@ export class InvoicesService implements OnModuleInit {
       where: { id },
       data: { status },
     });
+
+    // Enqueue webhook
+    await this.webhooksService.enqueueWebhook(id, status, updated.txHash);
+
     return this.normalizeInvoice(updated);
   }
 
@@ -136,6 +142,10 @@ export class InvoicesService implements OnModuleInit {
       where: { id },
       data: { status: "paid", txHash: txHash },
     });
+
+    // Enqueue webhook
+    await this.webhooksService.enqueueWebhook(id, "paid", txHash);
+
     return this.normalizeInvoice(updated);
   }
 
diff --git a/backend/src/stellar/soroban.integration.spec.ts b/backend/src/stellar/soroban.integration.spec.ts
index 4c0e392..20fbb26 100644
--- a/backend/src/stellar/soroban.integration.spec.ts
+++ b/backend/src/stellar/soroban.integration.spec.ts
@@ -107,13 +107,11 @@ describe("Soroban Integration", () => {
 
       await new Promise((resolve) => setTimeout(resolve, 100));
 
-      // eslint-disable-next-line @typescript-eslint/unbound-method
       expect(invoicesService.markAsPaid).toHaveBeenCalledWith(
         mockInvoice.id,
         "horizon-tx-hash-abc",
       );
 
-      // eslint-disable-next-line @typescript-eslint/unbound-method
       expect(sorobanService.recordPayment).toHaveBeenCalledWith({
         invoiceId: mockInvoice.memo,
         payer: mockPaymentRecord.from,
@@ -122,7 +120,6 @@ describe("Soroban Integration", () => {
         amount: "100000000",
       });
 
-      // eslint-disable-next-line @typescript-eslint/unbound-method
       expect(invoicesService.updateSorobanMetadata).toHaveBeenCalledWith(
         mockInvoice.id,
         "soroban-tx-hash-xyz",
@@ -146,11 +143,10 @@ describe("Soroban Integration", () => {
 
       await new Promise((resolve) => setTimeout(resolve, 100));
 
-      // eslint-disable-next-line @typescript-eslint/unbound-method
       expect(invoicesService.markAsPaid).toHaveBeenCalled();
-      // eslint-disable-next-line @typescript-eslint/unbound-method
+
       expect(sorobanService.recordPayment).toHaveBeenCalled();
-      // eslint-disable-next-line @typescript-eslint/unbound-method
+
       expect(invoicesService.updateSorobanMetadata).not.toHaveBeenCalled();
     });
 
@@ -179,7 +175,6 @@ describe("Soroban Integration", () => {
 
       await new Promise((resolve) => setTimeout(resolve, 100));
 
-      // eslint-disable-next-line @typescript-eslint/unbound-method
       expect(sorobanService.recordPayment).toHaveBeenCalledWith(
         expect.objectContaining({
           assetCode: "USDC",
diff --git a/backend/src/webhooks/webhooks.module.ts b/backend/src/webhooks/webhooks.module.ts
new file mode 100644
index 0000000..bc8201e
--- /dev/null
+++ b/backend/src/webhooks/webhooks.module.ts
@@ -0,0 +1,10 @@
+import { Module } from "@nestjs/common";
+import { PrismaModule } from "../prisma/prisma.module";
+import { WebhooksService } from "./webhooks.service";
+
+@Module({
+  imports: [PrismaModule],
+  providers: [WebhooksService],
+  exports: [WebhooksService],
+})
+export class WebhooksModule {}
diff --git a/backend/src/webhooks/webhooks.service.spec.ts b/backend/src/webhooks/webhooks.service.spec.ts
new file mode 100644
index 0000000..db93265
--- /dev/null
+++ b/backend/src/webhooks/webhooks.service.spec.ts
@@ -0,0 +1,152 @@
+import { Test, TestingModule } from "@nestjs/testing";
+import { WebhooksService } from "./webhooks.service";
+import { PrismaService } from "../prisma/prisma.service";
+import axios from "axios";
+
+jest.mock("axios");
+const mockedAxios = axios as jest.Mocked<typeof axios>;
+
+describe("WebhooksService", () => {
+  let service: WebhooksService;
+  let prisma: PrismaService;
+
+  const mockPrismaService = {
+    invoice: {
+      findUnique: jest.fn(),
+    },
+    webhookDelivery: {
+      create: jest.fn(),
+      findMany: jest.fn(),
+      update: jest.fn(),
+    },
+  };
+
+  beforeEach(async () => {
+    jest.clearAllMocks();
+
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        WebhooksService,
+        { provide: PrismaService, useValue: mockPrismaService },
+      ],
+    }).compile();
+
+    service = module.get<WebhooksService>(WebhooksService);
+    prisma = module.get<PrismaService>(PrismaService);
+  });
+
+  describe("enqueueWebhook", () => {
+    it("should enqueue a delivery if user has a webhook URL configured", async () => {
+      mockPrismaService.invoice.findUnique.mockResolvedValue({
+        id: "inv-1",
+        userId: "user-1",
+        user: { webhookUrl: "https://example.com/webhook" },
+      } as any);
+
+      await service.enqueueWebhook("inv-1", "paid", "hash-123");
+
+      expect(mockPrismaService.invoice.findUnique).toHaveBeenCalledWith({
+        where: { id: "inv-1" },
+        include: { user: true },
+      });
+      expect(mockPrismaService.webhookDelivery.create).toHaveBeenCalledWith(
+        expect.objectContaining({
+          data: expect.objectContaining({
+            invoiceId: "inv-1",
+            userId: "user-1",
+            url: "https://example.com/webhook",
+            status: "pending",
+            attempts: 0,
+          }),
+        }),
+      );
+    });
+
+    it("should skip enqueueing if no webhook URL is configured", async () => {
+      mockPrismaService.invoice.findUnique.mockResolvedValue({
+        id: "inv-2",
+        userId: "user-2",
+        user: { webhookUrl: null }, // no webhook URL
+      } as any);
+
+      await service.enqueueWebhook("inv-2", "paid", "hash-123");
+      expect(mockPrismaService.webhookDelivery.create).not.toHaveBeenCalled();
+    });
+  });
+
+  describe("deliver", () => {
+    it("should execute delivery successfully and update status", async () => {
+      mockedAxios.post.mockResolvedValue({ status: 200 } as any);
+
+      const delivery = {
+        id: "del-1",
+        url: "https://example.com/webhook",
+        payload: { status: "paid" },
+        attempts: 0,
+        user: { webhookSecret: "secret" },
+      };
+
+      await service.deliver(delivery);
+
+      expect(mockedAxios.post).toHaveBeenCalledTimes(1);
+      const postArgs = mockedAxios.post.mock.calls[0];
+      expect(postArgs[0]).toBe("https://example.com/webhook");
+      expect(postArgs[2]?.headers?.["x-invoisio-signature"]).toBeDefined(); // HMAC generated
+      expect(postArgs[2]?.headers?.["x-idempotency-key"]).toBe("del-1-0");
+
+      expect(mockPrismaService.webhookDelivery.update).toHaveBeenCalledWith({
+        where: { id: "del-1" },
+        data: expect.objectContaining({
+          status: "success",
+          attempts: 1,
+        }),
+      });
+    });
+
+    it("should apply exponential backoff on failure", async () => {
+      mockedAxios.post.mockRejectedValue(new Error("Timeout"));
+
+      const delivery = {
+        id: "del-2",
+        url: "https://example.com/webhook",
+        payload: { status: "paid" },
+        attempts: 1, // 1 past attempt
+        user: {},
+      };
+
+      await service.deliver(delivery);
+
+      expect(mockedAxios.post).toHaveBeenCalled();
+      expect(mockPrismaService.webhookDelivery.update).toHaveBeenCalledTimes(1);
+
+      const updateCall =
+        mockPrismaService.webhookDelivery.update.mock.calls[0][0];
+      expect(updateCall.where.id).toBe("del-2");
+      expect(updateCall.data.attempts).toBe(2);
+      expect(updateCall.data.status).toBeUndefined(); // Still 'pending' since not 5 retries
+      expect(updateCall.data.nextAttemptAt).toBeInstanceOf(Date);
+    });
+
+    it("should mark as failed permanently after 5 attempts", async () => {
+      mockedAxios.post.mockRejectedValue(new Error("Network Error"));
+
+      const delivery = {
+        id: "del-max",
+        url: "https://example.com/webhook",
+        payload: { status: "paid" },
+        attempts: 4, // meaning this attempt is the 5th
+        user: {},
+      };
+
+      await service.deliver(delivery);
+
+      expect(mockPrismaService.webhookDelivery.update).toHaveBeenCalledWith({
+        where: { id: "del-max" },
+        data: expect.objectContaining({
+          status: "failed",
+          attempts: 5,
+        }),
+      });
+    });
+  });
+});
diff --git a/backend/src/webhooks/webhooks.service.ts b/backend/src/webhooks/webhooks.service.ts
new file mode 100644
index 0000000..dce2ec8
--- /dev/null
+++ b/backend/src/webhooks/webhooks.service.ts
@@ -0,0 +1,175 @@
+import { Injectable, Logger } from "@nestjs/common";
+import { Cron, CronExpression } from "@nestjs/schedule";
+import { PrismaService } from "../prisma/prisma.service";
+import axios from "axios";
+import * as crypto from "crypto";
+
+@Injectable()
+export class WebhooksService {
+  private readonly logger = new Logger(WebhooksService.name);
+  private isProcessing = false;
+
+  constructor(private readonly prisma: PrismaService) {}
+
+  /**
+   * Enqueues a webhook delivery for an invoice status change if the user has a webhook URL configured.
+   */
+  async enqueueWebhook(
+    invoiceId: string,
+    status: string,
+    txHash: string | null,
+  ): Promise<void> {
+    const invoice = await this.prisma.invoice.findUnique({
+      where: { id: invoiceId },
+      include: { user: true },
+    });
+
+    if (!invoice || !invoice.user || !invoice.user.webhookUrl) {
+      if (!invoice?.user?.webhookUrl) {
+        this.logger.debug(
+          `Skipping webhook for invoice ${invoiceId}: No webhook URL configured for user.`,
+        );
+      }
+      return;
+    }
+
+    const payload = {
+      invoiceId: invoice.id,
+      status,
+      txHash,
+      timestamp: new Date().toISOString(),
+    };
+
+    await this.prisma.webhookDelivery.create({
+      data: {
+        invoiceId: invoice.id,
+        userId: invoice.userId!,
+        url: invoice.user.webhookUrl,
+        payload: payload,
+        status: "pending",
+        attempts: 0,
+        nextAttemptAt: new Date(), // try immediately or at the next cron tick
+      },
+    });
+
+    this.logger.log(
+      `Webhook enqueued for invoice ${invoiceId} and status ${status}.`,
+    );
+  }
+
+  /**
+   * Process the webhook queue periodically.
+   * Runs every minute.
+   */
+  @Cron(CronExpression.EVERY_MINUTE)
+  async processQueue() {
+    if (this.isProcessing) {
+      return;
+    }
+
+    this.isProcessing = true;
+    try {
+      const pendingDeliveries = await this.prisma.webhookDelivery.findMany({
+        where: {
+          status: "pending",
+          nextAttemptAt: { lte: new Date() },
+        },
+        take: 50,
+        include: { user: true },
+        orderBy: { createdAt: "asc" },
+      });
+
+      if (pendingDeliveries.length > 0) {
+        this.logger.log(
+          `Processing ${pendingDeliveries.length} pending webhook deliveries...`,
+        );
+      }
+
+      for (const delivery of pendingDeliveries) {
+        await this.deliver(delivery);
+      }
+    } catch (error) {
+      this.logger.error("Error processing webhook queue", error);
+    } finally {
+      this.isProcessing = false;
+    }
+  }
+
+  /**
+   * Delivers a single webhook payload, handling retries and HMAC signatures.
+   */
+  public async deliver(delivery: any): Promise<void> {
+    const user = delivery.user;
+    const secret = user?.webhookSecret;
+    const payloadStr = JSON.stringify(delivery.payload);
+
+    let signature = "";
+    if (secret) {
+      signature = crypto
+        .createHmac("sha256", secret)
+        .update(payloadStr)
+        .digest("hex");
+    }
+
+    // Adding idempotency key based on delivery ID and attempts
+    const idempotencyKey = `${delivery.id}-${delivery.attempts}`;
+
+    try {
+      await axios.post(delivery.url, delivery.payload, {
+        headers: {
+          "Content-Type": "application/json",
+          "x-invoisio-signature": signature,
+          "x-idempotency-key": idempotencyKey,
+        },
+        timeout: 5000,
+      });
+
+      // Update on success
+      await this.prisma.webhookDelivery.update({
+        where: { id: delivery.id },
+        data: {
+          status: "success",
+          lastAttemptAt: new Date(),
+          attempts: delivery.attempts + 1,
+        },
+      });
+
+      this.logger.log(`Webhook delivery ${delivery.id} succeeded.`);
+    } catch (error: any) {
+      const attempts = delivery.attempts + 1;
+      this.logger.warn(
+        `Webhook delivery ${delivery.id} failed (attempt ${attempts}): ${error.message}`,
+      );
+
+      if (attempts >= 5) {
+        await this.prisma.webhookDelivery.update({
+          where: { id: delivery.id },
+          data: {
+            status: "failed",
+            lastAttemptAt: new Date(),
+            attempts,
+          },
+        });
+        this.logger.error(
+          `Webhook delivery ${delivery.id} permanently failed after 5 attempts.`,
+        );
+      } else {
+        // Exponential backoff: Math.pow(2, attempts) minutes
+        // E.g., attempts: 1 -> 2m, 2 -> 4m, 3 -> 8m, 4 -> 16m
+        const nextAttempt = new Date();
+        nextAttempt.setMinutes(
+          nextAttempt.getMinutes() + Math.pow(2, attempts),
+        );
+
+        await this.prisma.webhookDelivery.update({
+          where: { id: delivery.id },
+          data: {
+            attempts,
+            lastAttemptAt: new Date(),
+            nextAttemptAt: nextAttempt,
+          },
+        });
+      }
+    }
+  }
+}
diff --git a/backend/testout.txt b/backend/testout.txt
new file mode 100644
index 0000000..1dcf4c6
--- /dev/null
+++ b/backend/testout.txt
@@ -0,0 +1,654 @@
+
+> invoisio-backend@0.0.1 pretest
+> npx prisma generate
+
+Loaded Prisma config from prisma.config.ts.
+
+Prisma schema loaded from prisma/schema.prisma.
+
+✔ Generated Prisma Client (v7.4.2) to ./node_modules/@prisma/client in 144ms
+
+Start by importing your Prisma Client (See: https://pris.ly/d/importing-client)
+
+
+
+> invoisio-backend@0.0.1 test
+> npx prisma generate && npx jest
+
+Loaded Prisma config from prisma.config.ts.
+
+Prisma schema loaded from prisma/schema.prisma.
+
+✔ Generated Prisma Client (v7.4.2) to ./node_modules/@prisma/client in 141ms
+
+Start by importing your Prisma Client (See: https://pris.ly/d/importing-client)
+
+
+PASS src/health/health.controller.spec.ts
+[Nest] 149468  - 03/07/2026, 4:27:07 PM   ERROR [WebhooksService] Webhook delivery del-max permanently failed after 5 attempts.
+PASS src/webhooks/webhooks.service.spec.ts
+PASS src/stellar/soroban.service.spec.ts
+PASS src/stellar/soroban.integration.spec.ts
+PASS src/auth/auth.service.spec.ts
+PASS src/stellar/stellar.service.spec.ts
+FAIL src/invoices/invoices.service.spec.ts
+  ● InvoicesService › DTO validation › should reject invalid invoice DTOs
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › DTO validation › should accept a valid dto and uppercase asset_code via transform
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › should be defined
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › findAll › should return paginated invoices
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › findAll › should return invoices with required fields within items
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › findOne › should return a single invoice by id
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › findOne › should throw NotFoundException for non-existent invoice
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › create › should normalize asset_code casing even when provided lowercase
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › create › should create a new invoice
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › create › should create an XLM invoice without asset_issuer
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › create › should generate a unique memo for each invoice
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › create › should add created invoice to the list
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › updateStatus › should update invoice status
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › findByMemo › should find invoice by memo
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+  ● InvoicesService › findByMemo › should return undefined for non-existent memo
+
+    Nest can't resolve dependencies of the InvoicesService (ConfigService, StellarService, SorobanService, PrismaService, ?). Please make sure that the argument WebhooksService at index [4] is available in the RootTestModule context.
+
+    Potential solutions:
+    - Is RootTestModule a valid NestJS module?
+    - If WebhooksService is a provider, is it part of the current RootTestModule?
+    - If WebhooksService is exported from a separate @Module, is that module imported within RootTestModule?
+      @Module({
+        imports: [ /* the Module containing WebhooksService */ ]
+      })
+
+    For more common dependency resolution issues, see: https://docs.nestjs.com/faq/common-errors
+
+      197 |
+      198 |   beforeEach(async () => {
+    > 199 |     const module: TestingModule = await Test.createTestingModule({
+          |                                   ^
+      200 |       providers: [
+      201 |         InvoicesService,
+      202 |         { provide: ConfigService, useValue: mockConfigService },
+
+      at TestingInjector.lookupComponentInParentModules (../node_modules/@nestjs/core/injector/injector.js:290:19)
+      at TestingInjector.resolveComponentWrapper (../node_modules/@nestjs/testing/testing-injector.js:19:45)
+      at resolveParam (../node_modules/@nestjs/core/injector/injector.js:140:38)
+          at async Promise.all (index 4)
+      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:169:27)
+      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:75:13)
+      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:103:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
+          at async Promise.all (index 3)
+      at TestingInstanceLoader.createInstancesOfProviders (../node_modules/@nestjs/core/injector/instance-loader.js:55:9)
+      at ../node_modules/@nestjs/core/injector/instance-loader.js:40:13
+          at async Promise.all (index 1)
+      at TestingInstanceLoader.createInstances (../node_modules/@nestjs/core/injector/instance-loader.js:39:9)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/core/injector/instance-loader.js:22:13)
+      at TestingInstanceLoader.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-instance-loader.js:9:9)
+      at TestingModuleBuilder.createInstancesOfDependencies (../node_modules/@nestjs/testing/testing-module.builder.js:118:9)
+      at TestingModuleBuilder.compile (../node_modules/@nestjs/testing/testing-module.builder.js:74:9)
+      at Object.<anonymous> (invoices/invoices.service.spec.ts:199:35)
+
+Test Suites: 1 failed, 6 passed, 7 total
+Tests:       15 failed, 36 passed, 51 total
+Snapshots:   0 total
+Time:        6.3 s, estimated 7 s
+Ran all test suites.
diff --git a/backend/tsout.txt b/backend/tsout.txt
new file mode 100644
index 0000000..e69de29