Webhook Tester
Inspect webhook data with MiniWebtool’s Webhook Tester. Review a payload, check a supported GitHub, Stripe, or Slack HMAC signature, or send a simulated request to examine an integration’s behavior.
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Click a service to load a realistic sample webhook payload.
About Webhook Tester
The Webhook Tester is a free, client-side tool designed for developers who work with webhook integrations. Whether you need to inspect a payload from Stripe, verify a GitHub signature, or simulate a POST request to your own endpoint, this tool handles webhook inspection and signature checks in your browser. Nothing is sent to our servers; the Request Simulator sends requests only to the URL you enter.
At a Glance
Webhook Tester inspects webhook payloads, verifies HMAC-SHA256 and HMAC-SHA1 signatures, and sends simulated POST requests to a URL you enter. Parsing and signature checks run in your browser.
| Feature | What you get | Good for |
|---|---|---|
| Payload inspector | Paste a JSON payload to get a syntax-highlighted tree with collapsible nodes and payload statistics. | Reading a webhook body from any provider |
| Signature verifier | Enter the payload, secret and received signature to check an HMAC-SHA256 or HMAC-SHA1 signature, as used by GitHub, Stripe and Slack. | Debugging why a signature check fails |
| Request simulator | Send a POST request with custom headers and a JSON body to a public URL, then view the response status, headers and body. | Testing your own endpoint |
| Sample payloads | Realistic sample payloads from GitHub, Stripe, Slack, Discord and Twilio, ready to inspect or use as templates. | Starting an integration without live events |
| Browser-side processing | Parsing and HMAC computation happen in your browser, so payloads and secrets are not sent to our servers. | Checking payloads that contain secrets |
| Copy output | Copy formatted payloads, computed signatures or generated cURL commands. | Sharing a failing request with a teammate |
What Is a Webhook?
A webhook (also called an HTTP callback or web callback) is an automated HTTP POST request that a service sends to your application when a specific event occurs. Instead of your application repeatedly polling an API for updates, the service proactively pushes event data to a URL you configure. Webhooks power real-time integrations across payment processing, version control, messaging, CI/CD pipelines, and more.
Key Features
🔍 Payload Inspector
Paste any JSON webhook payload and get an interactive tree view with syntax highlighting, collapsible nodes, and payload statistics.
🔐 Signature Verifier
Verify HMAC-SHA256 and HMAC-SHA1 webhook signatures to ensure payloads haven't been tampered with. Works with GitHub, Stripe, Slack, and any HMAC-based system.
📡 Request Simulator
Send HTTP POST requests with custom headers and JSON bodies to any public endpoint. View response status, headers, and body in real time.
📦 Sample Webhooks
Explore realistic sample payloads from popular services including GitHub, Stripe, Slack, Discord, and Twilio — ready to inspect or use as templates.
🛡️ 100% Client-Side
All parsing, HMAC computation, and formatting happens in your browser. No payloads, secrets, or tokens are ever sent to our servers.
📋 One-Click Copy
Copy formatted payloads, computed signatures, or auto-generated cURL commands with a single click for easy sharing and testing.
How to Use This Tool
- Choose a mode: Select one of four tabs — Payload Inspector, Signature Verifier, Request Simulator, or Sample Webhooks.
- Enter your data: Paste a webhook payload, enter a signature to verify, configure a request, or pick a sample webhook from popular services.
- Run the action: Click the action button to parse, verify, send, or load the selected webhook data.
- Review results: Examine the parsed tree view, verification result, response details, or formatted sample payload.
Webhook Security: Why Signatures Matter
When a webhook is sent over the internet, there's no guarantee that the payload came from the service you expect. An attacker could forge a request to your endpoint with a malicious payload. HMAC signatures solve this problem: the sender computes a hash of the payload using a shared secret, and includes it in a header. Your server recomputes the hash and verifies it matches — if it does, the payload is authentic and untampered.
Common signature headers include X-Hub-Signature-256 (GitHub), Stripe-Signature (Stripe), and X-Slack-Signature (Slack). Our Signature Verifier tab lets you test this process directly in the browser.
Common Webhook Providers
GitHub
GitHub sends webhooks for repository events like pushes, pull requests, issues, releases, and more. Signatures use HMAC-SHA256 with the X-Hub-Signature-256 header.
Stripe
Stripe sends payment event webhooks (charges, subscriptions, invoices). They use a timestamp-based signature scheme with the Stripe-Signature header containing t= and v1= components.
Slack
Slack sends interaction payloads and event subscriptions. Signatures use HMAC-SHA256 with the X-Slack-Signature header and a versioned signing scheme (v0: prefix).
Discord
Discord interaction webhooks include Ed25519 signatures. Event payloads contain interaction data for slash commands, buttons, and modals.
Twilio
Twilio sends status callbacks for SMS, voice calls, and other communications events. Payloads are typically form-encoded with fields like MessageSid, From, and Body.
Frequently Asked Questions
What is a webhook?
A webhook is an HTTP callback that sends real-time data from one application to another when a specific event occurs. Instead of polling an API repeatedly, webhooks push data to your endpoint automatically, making them efficient for event-driven architectures.
How do I verify a webhook signature?
Webhook signatures are verified by computing an HMAC hash of the payload using a shared secret key and comparing it to the signature sent in the request header. Use the Signature Verifier tab to paste your payload, secret, and received signature to check if they match.
Is my webhook data safe with this tool?
Yes. All processing happens entirely in your browser using client-side JavaScript. No webhook payloads, secrets, or signatures are ever sent to our servers. The Request Simulator sends requests only to the URL you enter; nothing is sent to our servers.
What webhook providers does this tool support?
The Sample Webhooks tab includes pre-built payloads for GitHub, Stripe, Slack, Discord, and Twilio. The Payload Inspector and Signature Verifier work with any JSON webhook payload from any provider.
Can I send test webhook requests from this tool?
Yes. The Request Simulator tab lets you send HTTP POST requests with custom headers and a JSON body to any publicly accessible URL. Note that the target server must allow cross-origin requests (CORS) for the browser to receive the response.
Additional Resources
Reference this content, page, or tool as:
"Webhook Tester" at https://MiniWebtool.com/webhook-tester/ from MiniWebtool, https://MiniWebtool.com/
by miniwebtool team. Updated: Mar 7, 2026
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