Point it at a Model Context Protocol endpoint. It runs the initialize handshake, lists the tools the server exposes, builds a form from each tool's JSON Schema, and shows you the raw JSON-RPC underneath every exchange.
Requests are relayed through this app's own proxy, because MCP servers are built for server-to-server clients and almost never send the CORS headers a browser needs. The proxy refuses private and reserved addresses, so it cannot be pointed at anything inside a network.
Servers you connect to appear here.