Webhook Tester API

MCP Server x402 License: MIT

Test webhook endpoints -- send POST/PUT/PATCH/DELETE with custom headers and payloads. Measure latency and TLS. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.

Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.

Quickstart -- MCP

Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):

{
  "mcpServers": {
    "webhook-tester": {
      "url": "https://webhook-tester.api.klymax402.com/mcp"
    }
  }
}

Quickstart -- HTTP (x402)

curl -X POST "https://webhook-tester.api.klymax402.com/api/test" \
  -H "Content-Type: application/json" \
  -d '{"url":"https://example.com"}'
# -> 402 Payment Required, with an x402 payment challenge in the response body

Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.

Tools

Tool	Method	Path	Price	Description
api_test_webhook	POST	/api/test	$0.002	Send a test request to a webhook URL and analyze the response

api_test_webhook

Use this when you need to test a webhook endpoint by sending a request with custom headers, body, and method. Returns full response data in JSON.

Parameters

Name	Type	Required	Description
url	string	yes	Webhook URL to test (must be https)
method	string	no	HTTP method: POST, PUT, PATCH, DELETE (default: POST)
headers	object	no	Custom headers as key-value pairs
body	object	no	JSON body to send
timeout	number	no	Timeout in seconds (default: 10, max: 30)

Example response:

{"url":"https://hooks.example.com/callback","method":"POST","statusCode":200,"responseBody":{"received":true},"latency":142,"tlsInfo":{"protocol":"TLSv1.3","cipher":"AES-256-GCM"},"requestSize":256,"responseSize":48}

When to use: testing webhook integrations, debugging API callbacks, validating endpoint availability, and measuring webhook response times.

Not for: web scraping (use web_scrape_to_markdown), screenshot capture (use capture_screenshot), HTTP header security audit (use network_analyze_headers).

Example agent prompts

• "Test a webhook endpoint by sending a request with custom headers, body, and method"

Payment

• Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
• Network: Base L2 (eip155:8453)
• Asset: USDC
• Facilitator: Coinbase CDP (primary), PayAI (fallback)
• Also reachable via ATXP (OAuth-wrapped x402, RFC 9728 protected-resource metadata)

Part of klymax402

100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.

• Catalog: https://klymax402.com/llms.txt
• Full API reference: https://klymax402.com/llms-full.txt
• Live stats: https://klymax402.com/stats

License

MIT