Summary
Reach for this when you need to validate webhook integrations without spinning up your own infrastructure. It connects to a hosted endpoint at webhook-tester.api.klymax402.com and runs over SSE transport. You can fire test requests at webhook URLs, measure response latency, and validate payloads coming back. The x402 micropayment integration suggests it's metered usage, though the GitHub repo doesn't expose implementation details beyond TypeScript source. Useful for debugging third-party webhook configs or load testing callback handlers before you wire them into production systems.
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Tools
Public tool metadata for what this MCP can expose to an agent.
1 tools
api_test_webhookUse 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. Returns: 1. statusCode 2. responseBody (parsed JSON o5 params
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. Returns: 1. statusCode 2. responseBody (parsed JSON o
Parameters* required
bodyobjectJSON body to send
headersobjectCustom headers as key-value pairs
methodstringHTTP method: POST, PUT, PATCH, DELETE (default: POST)
timeoutnumberTimeout in seconds (default: 10, max: 30)
urlstringWebhook URL to test (must be https)
Webhook Tester API
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 | $0.005 | 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
Featured
Plug Mailtrap into your AI workflow and let it handle the email.
Connect Mailtrap MCP →Agent, run crypto. Access onchain data & trade routes via 1inch.
Install now →Make coding agent sessions - Searchable, Shareable, Vendor-neutral & Scored.
Try For Free →Your agent targets a perfect 10 Code Health score. Deterministic. Every commit.
Try For Free →Integrate web data into your AI product. One API to scrape website & brand data.
Get API Key Now →belt cli automatically finds the best tools and skills for your agent. image, video, music, tts...
one prompt install →
