Webhook Tester & Inspector

What Is Webhook Testing

Webhooks are HTTP callbacks that deliver real-time notifications from one application to another when specific events occur. Unlike polling (repeatedly checking for updates), webhooks push data instantly — making them the backbone of modern integrations between SaaS platforms, payment processors, CI/CD systems, and communication tools.

Testing and debugging webhooks is notoriously difficult because they require a publicly accessible URL to receive the callback, the sending service controls when events fire, and payload formats can be complex. This tool provides a webhook endpoint for receiving, inspecting, and debugging webhook payloads.

How Webhooks Work

1. Registration — You register a callback URL with the sending service (e.g., Stripe, GitHub, Slack)
2. Event occurs — Something happens in the sending service (payment completed, code pushed, message posted)
3. HTTP POST — The service sends an HTTP POST request to your URL with event data in the body
4. Processing — Your endpoint receives the payload, validates it, and processes the event
5. Response — Your endpoint returns a 2xx status code to acknowledge receipt

Common Webhook Providers

Common Use Cases

• Integration development: Test webhook endpoints during development by receiving real or simulated payloads and inspecting their structure
• Debugging delivery failures: When webhooks are not being received, test the endpoint directly to determine if the issue is network, authentication, or parsing
• Payload format analysis: Inspect the exact JSON structure, headers, and metadata that a webhook provider sends to document integration requirements
• Retry behavior testing: Understand how providers handle failed deliveries (retry intervals, exponential backoff, dead letter queues) by simulating error responses
• Security validation: Verify that your webhook signature verification logic correctly validates authentic payloads and rejects tampered ones

Best Practices

1. Always verify webhook signatures — Never trust webhook payloads without cryptographic verification. Providers include HMAC signatures that prove the payload was sent by them and not tampered with.
2. Return 200 quickly — Process webhooks asynchronously. Return a 200 status immediately and process the event in a background job. Slow responses cause providers to retry or disable your endpoint.
3. Handle duplicate deliveries — Webhooks can be delivered multiple times (provider retries, network issues). Use idempotency keys or event IDs to prevent processing duplicates.
4. Log all payloads — Store raw webhook payloads before processing. When something goes wrong, you need the original data for debugging and replay.
5. Implement retry handling — Design your endpoint to handle the provider's retry behavior. If your endpoint fails, the provider will retry — potentially delivering the same event multiple times.