"Feishu - A Collaboration and Messaging Platform" matching MCP connectors:

Detect breaking changes, generate changelogs, diff, and validate OpenAPI specs.

Free platform to test MCP clients without installing anything. Create mock tools with dynamic templates, configurable delays, conditions (if/then), and response sequences. Supports JSON-RPC 2.0 over Streamable HTTP. Built-in text_echo and json_echo tools. Rate-limited tiers: anonymous (5 calls/min, 1 mock tool), registered (10 calls/min, 4 mock tools), premium (60 calls/min, unlimited). Zero setup — no install, no registration required. More info: https://www.testmcp.dev

Instant no-signup webhook & HTTP-request inspector for testing webhooks and agent tool-callbacks.

A webhook inbox for agents: one call returns a live URL. Mock, verify, inspect and replay.

Deploy production REST APIs from JSON schemas in seconds. Manage projects, schemas, and deployments.

Keyless webhook endpoints: capture, wait, replay, forward, and generate types from real traffic.

Discover, pay for, execute, and publish APIs through Apiosk.

Debug webhooks from your AI agent: inspect and replay captured webhooks on localhost.

End-to-end API testing — generate and run tests from OpenAPI, curl, Postman, or real user traffic.

Swagger Petstore API (v1.0.27) as MCP for testing and prototyping powered by the HAPI MCP server

40+ developer tools from Context7, Code Runner, Python Execute, NPM Sentinel, PlantUML, and Microsoft Learn. Docs lookup, code execution, security scanning. Starts at $0.01/call. Get your API key at app.xpay.sh or xpay.tools

Public benchmark where agents submit Q&A answers and get scored on a leaderboard.

Manage your Nahook webhooks from your AI client — inspect deliveries, retry failures, and manage endpoints. Connects over OAuth, no API keys

MCP server and REST API for querying OpenAPI specs. Endpoint-level extraction, schema resolution, 100+ APIs indexed.

A basic MCP server to operate on the Postman API.

Receive, inspect, replay and deliver webhooks — with signature verification and agent triggers.

Free *.pntr.dev dev subdomains — register subdomains, manage DNS and wildcard records, receive email on disposable inboxes, and capture HTTP requests for webhook debugging. OAuth sign-in; free tier.

Monitor MCP servers, API contracts and AI outputs for schema drift. Alerts on breaking changes.

Simceptor is an AI-native Mock API simulation platform with a built-in MCP server. It enables AI agents to create, inspect, update, and test dynamic mock APIs, conditional response rules, stateful session simulations, and network latency directly from context.

A paid remote MCP for developer endpoint scanner MCP, built to return verdicts, receipts, usage logs