"Semgrep static analysis tool" matching MCP connectors:

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

MCP tool observatory: do registry servers answer, and are their answers true? No key.

Check an MCP endpoint resolves: liveness, live tool list, schema drift. Free.

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

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