A local MCP server that breaks on demand, allowing you to test your client against auth failures, disappearing tools, flaky responses, and token expiry from a web UI.
A mock MCP server for testing MCP client implementations and development workflows. Supports tools, prompts, and resources across multiple transport protocols (stdio, HTTP, SSE).
A configurable mock MCP server with a live web UI that lets developers define tools, point their MCP clients at it, and watch every JSON-RPC message in both directions to debug client behavior such as initialization, tool list refreshes, and error handling.