<MCP.Playground/>
online

MCP Tester

FreeNo Sign-up

Free MCP tester that runs entirely in your browser. Paste any MCP server URL and inspect every tool, prompt, and resource — then call them with real arguments and see live JSON-RPC traffic. Works with HTTP + SSE and Streamable HTTP servers.

Want to test it with an AI?

See exactly how Claude, GPT and Gemini call your tools in real conversations — then save the setup as a reusable agent.

Test with AI →Browse templates

✦ Free credits on sign-up · no credit card

Loading MCP tester…

Need a quick security check too?

Test for HTTPS, authentication, security headers, CORS and 14 more — free MCP server security audit.

Run Security Scan →

MCP weekly digest

New servers, security advisories, and tutorials — straight to your inbox. No spam.

What is an MCP Tester?

An MCP tester is a tool that connects to a Model Context Protocol server, lists everything the server exposes (tools, prompts, resources), and lets you call those capabilities with real input — so you can verify the server actually does what its schema promises before wiring it into Claude Desktop, Cursor, or Claude Code.

This MCP tester runs entirely in your browser. There is nothing to install, no CLI to configure, and no API keys to manage. Paste a URL, click connect, and you are testing.

How to use the MCP tester

  1. Paste your server URL — e.g. https://mcp.example.com/sse or a Streamable HTTP endpoint
  2. Add a Bearer token if the server requires authentication
  3. Connect — the tester runs the MCP initialize handshake and lists capabilities
  4. Click a tool to see its input schema, then fill in arguments and run it
  5. Inspect the JSON-RPC log to see exactly what the server returned

Need a server to point at? Browse the MCP servers directory for live remote endpoints.

What this MCP tester checks

  • Tool discovery — calls tools/list and renders each tool with its input schema
  • Tool execution — runs tools/call with the arguments you provide, surfaces errors verbatim
  • Prompt templates — fetches and renders prompts/list and prompts/get output
  • Resources — lists exposed resources and reads them via resources/read
  • Protocol-level logs — every JSON-RPC frame is shown raw for debugging
  • Auth flows — supports Bearer tokens, including refresh on 401

MCP tester vs MCP inspector

The two terms get used interchangeably. The official MCP Inspector from Anthropic is a local Node tool you run with npx @modelcontextprotocol/inspector. This in-browser MCP inspector online does the same job for remote (HTTP / SSE / Streamable HTTP) servers — without any local setup.

For STDIO servers that run as a child process on your machine, use the local inspector. For everything else, paste the URL above.

Frequently Asked Questions

Is this MCP tester really free?
Yes. Connecting to a server and running any number of tool calls, prompt lookups, or resource reads is free, with no sign-up, credit card, or rate limit on the tester itself.
Which MCP transports does it support?
HTTP + SSE (the original remote transport) and Streamable HTTP (the newer bidirectional transport from the 2025 spec). STDIO servers require a local runtime and are not testable in-browser.
Can I test an MCP server that needs authentication?
Yes — paste a Bearer token in the auth field. The tester sends it on every request and surfaces 401s in the log if the token is wrong or expired.
Does the tester store my server URL or tokens?
No. Everything stays in your browser session. We do not log the URLs you connect to or the tokens you paste.
Where do I find MCP servers to test?
Browse the MCP servers directory or read the awesome MCP servers list for 70+ curated servers with remote URLs ready to paste.
How do I check my MCP server is secure too?
Run the free MCP security scanner — paste your server URL and it runs 20+ checks across HTTPS, authentication, TLS, security headers, CORS, error verbosity and rate limiting.

Related tools

MCP Tester — Free Online MCP Server Testing Tool (No Install) | MCP Playground