API Integration Tester
End-to-end testing for payment flows, webhooks, and multi-step integrations. No mocking frameworks needed.
Quick Answer
Tools like Postman, Hoppscotch, and Insomnia test outbound API calls (you send a request, get a response). But they don't test inbound webhooks—when a third party (Stripe, GitHub, Shopify) sends data to your endpoint. Requex.me fills the gap: get a free webhook URL, configure your API to call it, inspect payloads in real-time, and test multi-step flows (authenticate → fetch → webhook → retry).
The Gap in API Testing Tools
Traditional API testing tools excel at outbound requests:
Postman, Hoppscotch, Insomnia workflow:
- Write a request (GET /users, POST /payments)
- Click "Send"
- See the response (200 OK, 401 Unauthorized, etc.)
- Done
This works great for testing your backend's API endpoints. But modern integrations are bidirectional. Stripe calls your webhook. GitHub sends push events. Shopify notifies you when orders change. How do you test that flow without a deployed server?
Three Multi-Step Integration Scenarios
Scenario 1: Payment → Webhook → Order Status
Your storefront collects a payment via Stripe. Stripe calls your webhook when the payment succeeds. Your backend should update the order status to "paid" and send a confirmation email.
Traditional testing: Deploy to staging, use ngrok or Stripe CLI, mock Stripe locally, or skip the webhook test entirely.
With Requex: Get a webhook URL, register it with Stripe (use test mode). Create a test payment in Stripe Dashboard. Watch the webhook arrive in Requex instantly. Inspect the payload, verify your signature verification logic works, confirm your webhook handler would update the order. All without ngrok or deployment.
Scenario 2: Auth → Resource Fetch → Forwarding
You're building a CRM integration. You receive a webhook from your source system (HubSpot, Salesforce). Your handler authenticates to the destination API (another SaaS tool), creates a resource (contact, deal), and logs the result. If the destination is slow or fails, you need to retry with backoff.
With Requex: Register a webhook endpoint. Requex has built-in forwarding rules: when a webhook arrives, automatically forward it to your destination API with custom headers, retry settings, and delay. Watch both the inbound webhook and the outbound forwarding logs in one dashboard. No code required for testing the forwarding behavior.
For more details, see webhook authentication and webhook fanout.
Scenario 3: Webhook Registration → Event Trigger → Retry Loop
Some APIs (GitHub, Stripe, n8n) let you register a webhook URL via their API. You call POST /webhooks with your endpoint URL. The API validates it by sending a test ping. If validation fails, the webhook registration fails. If it succeeds, you're live.
With Requex: Use the Requex URL as your webhook endpoint during registration. When the API sends its validation ping, Requex captures it. Inspect the ping in Requex's dashboard to understand what the API expects (signature algorithm, required headers, etc.). Then create a real event in the API. Watch the webhook arrive. Test your retry logic by simulating a failure response (500 error, timeout) and seeing how many times the API retries.
Mocking Approaches for Testing
1. Specification-Driven Mocking (Prism, Mockoon)
Tools like prism (by Stoplight) read an OpenAPI spec and auto-generate a mock server. Example: you have a Stripe API spec, Prism generates a mock Stripe endpoint that responds to POST /charges with a valid response. You test against the mock, not the real API.
Pros: Fast, deterministic, no rate limits. Cons: Spec might be incomplete; mocks don't match production edge cases.
2. Behavioral Mocking (WireMock, VCR.py)
Tools like wiremock or VCR.py record real API interactions (request + response) and replay them in tests. First test run: hit the real API, record responses. Subsequent runs: VCR intercepts requests and returns recorded responses.
Pros: Guaranteed accuracy (real responses). Cons: Setup overhead; recordings go stale; doesn't test new failure scenarios.
3. Real Endpoint Mocking (Requex.me)
Instead of mocking the third-party API, get a real webhook endpoint (Requex URL). Use the third party's real test mode (Stripe test keys, GitHub test repo, Shopify dev store). Real webhooks arrive at your Requex endpoint. You see real payloads, real signatures, real retry behavior.
Pros: Most realistic; tests actual webhook flow; no vendor-specific mocking setup. Cons: Slower (wait for webhook); requires third-party test mode access.
Requex as Your Integration Test Dashboard
Requex.me combines three capabilities for end-to-end API integration testing:
| Capability | Use Case | Example |
|---|---|---|
| Webhook Endpoint | Capture inbound events | Stripe sends charge.succeeded → captured in Requex |
| Response Config | Simulate success/failure | Return 500 error to test webhook retry logic |
| Forwarding Rules | Multi-step flows | Webhook → forward to your backend → forward to CRM |
Use Requex for the 80% of integration testing that doesn't require mocking frameworks. For unit tests and CI/CD, use Prism or VCR. For manual testing and debugging, use Requex.
Common API Integration Test Scenarios
Test Signature Verification
Stripe, GitHub, and Shopify all sign their webhooks. Use Requex to send test payloads with the correct signature header. Verify your HMAC validation logic works before deployment. See Stripe webhook testing and Shopify webhook testing for platform-specific examples.
Test Idempotency
Send the same webhook twice. Verify your handler doesn't create duplicate database records. Use Requex to replay a captured webhook by sending the same payload multiple times.
Test Retry Logic
Use Requex's response config to simulate timeouts, 500 errors, or slow responses. Verify the third-party API retries with backoff. Count the number of delivery attempts in Requex's dashboard.
Test Data Transformation
Capture a real webhook payload in Requex. Save it. Replay it with your backend code. Verify data is transformed, stored, and forwarded correctly. Use Requex's forwarding rules to verify multi-hop flows (webhook → your backend → CRM API).
Getting Started
- Visit Requex.me and copy your unique webhook URL (no signup required).
- In the third-party service (Stripe, GitHub, Shopify), register your Requex URL as a webhook endpoint.
- Trigger an event in the service (create a test payment, push code, place an order).
- Watch the webhook arrive in real-time in your Requex dashboard.
- Inspect the payload, headers, and signature. Test your webhook handler locally against this payload.
- Once confident, deploy to production and register your real endpoint.
See Also
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