webhook-capture-mcp

Let your AI assistant see your webhooks. A self-hosted MCP server that captures incoming webhook/HTTP requests and lets Claude, Cursor, or VS Code inspect, wait for, and replay them — so you can debug "why isn't my webhook working?" by having the AI read the actual payload.

You're wiring up a Stripe event, a GitHub webhook, an n8n/Make callback. Something fires, but you can't see what it sent. Instead of reaching for webhook.site and copy-pasting into chat, point the webhook here and ask your assistant: "what did that request contain?"

What it does

• 🎣 Captures every incoming request (method, path, query, headers, raw + parsed JSON body)
• 🔍 Inspects any captured request in full detail on demand
• ⏳ Waits for the next request — "I'll wait, trigger your webhook now"
• ♻️ Replays a captured request to any URL (e.g. your local dev server)
• 🏠 Self-hosted, zero infrastructure — runs on your machine via npx, stores nothing in the cloud

Install

Add it to your MCP host. It runs via npx — no separate install step.

Claude Desktop / Claude Code (claude_desktop_config.json or .mcp.json):

{
  "mcpServers": {
    "webhook-capture": {
      "command": "npx",
      "args": ["-y", "webhook-capture-mcp"],
      "env": { "WEBHOOK_CAPTURE_PORT": "4444" }
    }
  }
}

Cursor (~/.cursor/mcp.json) and VS Code (.vscode/mcp.json, Copilot agent mode) use the same shape. Restart the host, and you'll see the webhook-capture tools.

Use it

1. Ask your assistant to run capture_status — it prints the local capture URL (http://localhost:4444) and how to expose it.
2. Point a webhook at it.
   • Local sender (your own app, curl): hit http://localhost:4444/anything directly.
   • External sender (Stripe, GitHub…): run a tunnel on your machine and use its public URL:

     ngrok http 4444
     # or:  cloudflared tunnel --url http://localhost:4444
     

     Put the printed https://… URL in your provider's webhook settings.
3. Ask: "wait for the next webhook and tell me what's in it" → the assistant calls wait_for_request, you trigger the event, and it reads back the full payload.
4. Ask: "replay that to my local server at http://localhost:3000/webhook" → replay_request.

Tools

Tool	Description
capture_status	Show the capture URL, count, and how to expose it via a tunnel
list_requests	List captured requests (newest first); filter by method / path
get_request	Full detail of one request by id
wait_for_request	Block until the next request arrives (or timeout)
replay_request	Re-send a captured request to a target URL, return the response
clear_requests	Empty the store

Configuration

Env var	Default	Description
WEBHOOK_CAPTURE_PORT	4444	Port the capture listener binds to
WEBHOOK_CAPTURE_HOST	127.0.0.1	Bind address. Loopback by default (tunnels still reach it). Set to 0.0.0.0 for direct LAN senders.

Notes & limits (v0.1)

• In-memory only — keeps the last 100 requests; restarting clears them. (Persistence is planned.)
• No auth on the capture endpoint. It binds to loopback by default. If you expose it via a tunnel, treat the tunnel URL as sensitive and shut it down when done.
• Bodies are capped at 5 MB.

Run from source

git clone https://github.com/void-pulse/webhook-capture-mcp
cd webhook-capture-mcp
npm install && npm run build
node dist/index.js   # speaks MCP over stdio

License

MIT © Curtis Holmes