"How to perform SELECT queries in PostgreSQL" matching MCP connectors:

Simulate, test, and analyze cloud architectures without deploying real infrastructure. Cloud World Model enables AI agents to model cloud environments, evaluate architecture behavior and costs, run failure and chaos simulations, and explore infrastructure scenarios across cloud providers.

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

Check that your AI is being logical. Free tool that mathematically catches contradictions in agent reasoning. No account needed. Also offers paid guardrails that converts natural language to formal verification proofs, that anyone can check succinctly.

Hosted MCP server to lint SKILL.md files: packaging checks, regex tests, JSON validation, diffs.

X-Z-CS AI validation with auditable reasoning. 8 active tools; 5 in maintenance. v0.5.61

Give AI coding agents access to your Vynix visual feedback, bug reports, and AI diagnosis.

Accessibility pre-checks (WCAG/BFSG) in a real browser + statement drafts. Pay per call.

Verifies AI agent work end to end: real artifacts and outcomes checked, not self-reported success.

Grade MCP servers A to F with the open behavioral litmus. npm: full toolset; hosted: lookups only.

Check if your MCP server is ready to publish on the MCP Registry, Smithery, or npm.

Validate up to 75,000 URLs per job (status, redirects, response times). OAuth 2.1.

Pre-commit code quality guardian. Detects semantic drift in AI-generated code.

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

Rule engine with built-in simulation. 55 MCP tools for complete business rule lifecycle management.

Agentic code review, no signup to try: reality gates + frontier-model review, with veto.

MCP server providing access to the Scorecard API to evaluate and optimize LLM systems.

MCP server for AI access to SmartBear tools, including BugSnag, Reflect, Swagger, PactFlow, QTM4J.

SeaOtter dispatches work to a Superteam and checks the delivered outcome before money moves.

AI QA that runs your app in a browser on every pull request: projects, test targets, test cases.

Deploy AI user personas to validate user journeys at scale. Find UX friction before real users do.