"Resources or services available for free" matching MCP connectors:
GET /v1/connectors – MCP directory API referenceMatching Connector Tools:
Conformance checker for MCP servers. Free, no key, verdicts recomputable and re-measured daily.
A webhook inbox for agents: one call returns a live URL. Mock, verify, inspect and replay.
Remote MCP that evaluates one public HTTPS URL for WebMCP readiness: intent, tools observed, what to add, what never to expose.
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
Independent health, price and history for x402/MPP endpoints. Metered over x402; free grade on web.
What is known to be broken in an MCP server or API operation, with the check that found it.
Paid OpenAPI audit and API change detection for agents. $0.10 USDC per analysis via x402 on Base.
AI-callable tools for API mocking, testing, monitoring, security, and automation.
Webhook URLs for AI agents: receive, wait for, replay, sign and verify webhooks (Stripe, GitHub…).
Point Claude Code, Qwen Code, Cursor, or any MCP client at https://docs.jmeter.ai/api/mcp and your agent answers JMeter questions grounded in this documentation, with a source link for every answer. Free, no API key, no signup.
Ephemeral HTTPS inbox for bots: mint URL, capture POSTs, list JSON. TEST. https://inbox.kymac.co
Ephemeral mailboxes and a mock OAuth IdP for testing email and auth flows — 39 API-driven tools covering mailboxes, mails, attachments, domains, teams, and mock identities.
AI-operated. Free previews: licences, page reads, endpoint checks. Paid full versions over x402.
Web search for agents, one x402 payment: real results, provider failover, signed receipt. $0.01.
Test FIX from Claude, ChatGPT, or Cursor: free sandbox FIX sessions or your own FIXSIM instances.
Free agent-service discovery, OpenAPI document checks, and receipt verification. No API key needed.
{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"whoami","arguments":{}}} free no key
Free agent tests (no account or payment); paid ping.
Experimental MCP server for current empirical verification of explicit public HTTPS endpoint claims.
Webhook capture bins for agents: get a URL, wait for webhooks, set replies, verify signatures.
