MCP Explorer

Browser-based explorer for MCP servers over streamable HTTP or stdio — list and invoke tools with auto-generated forms.

Install

npm install -g @orenvill/mcp-explorer

The -g flag installs globally, making the mcp-explorer command available anywhere in your terminal.

Requirements: Node.js 20 or later (node --version).

Upgrading from an older install? If you previously used npm install -g mcp-explorer or npm install -g github:OrenVill/mcp-explorer, uninstall first:

npm uninstall -g mcp-explorer
npm install -g @orenvill/mcp-explorer

Run

mcp-explorer              # start + open browser at http://127.0.0.1:4173/
mcp-explorer 3000         # custom port
mcp-explorer --no-open    # skip opening the browser (also: OPEN=0)

Update

npm update -g @orenvill/mcp-explorer

What it does

Point it at any MCP server:

• HTTP — streamable HTTP endpoint (typically http://host:port/mcp)
• Stdio — local subprocess (command, args, optional cwd and env), same as Cursor/Claude Desktop MCP config

The explorer auto-connects, lists all available tools, and generates input forms from each tool's JSON Schema so you can invoke them immediately from the browser.

Stdio note: stdio servers use a local Node bridge built into mcp-explorer. You must run the app via mcp-explorer (or npm run dev from source) — opening static files alone does not spawn subprocesses.

• Add / edit / remove HTTP or stdio MCP servers — persisted to localStorage
• Stdio bridge for local command-based MCP servers (requires mcp-explorer or npm run dev)
• Local proxy mode for HTTP MCP servers that do not expose browser CORS headers
• Auto-discovered tool list via tools/list
• Generated forms for strings, numbers, booleans, enums, and JSON objects/arrays
• Protocol Inspector timeline for debugging MCP calls, results, errors, and durations
• Schema Lab for inspecting tool schemas, generating example args, and copying JSON-RPC calls
• Permission Surface audit, Prompt Injection scan, and Observation Journal for MCP trust evaluation
• Meta-tool discovery with one-click Discover all tools

Full documentation

github.com/OrenVill/mcp-explorer

License

MIT