Getting Started
Connecting Servers
MCP Playground connects to any MCP server that exposes a remote endpoint — Streamable HTTP, SSE, or WebSocket transport.
Step 1 — Go to the Connect page
Navigate to /connect and paste your server's URL. MCP Playground supports three transport types:
Streamable HTTP (recommended)
https://your-server.com/mcpThe newer MCP transport. Tried first on every connection.
SSE (Server-Sent Events)
https://your-server.com/sseLegacy SSE transport. Automatically tried as a fallback if Streamable HTTP fails.
WebSocket
wss://your-server.com/mcpFor servers that use WebSocket transport. Use ws:// or wss:// URLs — connected directly via the MCP SDK.
Note: For HTTP URLs, MCP Playground tries Streamable HTTP first, then falls back to SSE automatically. For WebSocket URLs (ws:// / wss://), it connects directly.
Step 2 — Add auth headers (if required)
Many servers require authentication. MCP Playground lets you add arbitrary HTTP request headers on the Connect page. Common patterns:
Bearer token (most common)
API key header
Custom header
Privacy note: Auth headers are stored in sessionStorage only — they exist for the duration of your browser session and are never persisted to our servers. They are sent in the POST body of our API route and forwarded to your MCP server.
Step 3 — Inspect the server
After connecting, MCP Playground fetches all tools, resources, and prompts your server exposes. You'll see:
- →A list of all tools with their names, descriptions, and input schemas
- →A list of resources with URI, mime type, and description
- →A list of prompts with their argument schemas
- →Server metadata (name, version, protocol version)
Step 4 — Test tools in the Playground
Click Open in Playground from the inspect page. The Playground lets you:
- →Select any tool from the sidebar
- →Fill in arguments using an auto-generated form based on the tool's JSON Schema
- →Execute the tool and see the full response
- →Browse execution history (persisted in localStorage)
- →Share a reproducible link with pre-filled args
- →Generate config snippets to add the server to Claude Desktop, Cursor, or Claude Code
Troubleshooting
Connection failed
Make sure the server URL is publicly accessible and not behind a firewall or VPN. Localhost URLs are blocked in production — use supergateway to expose a local server.
Timeout
The server took more than 10 seconds to respond to the initial connection. Check if the server is running and healthy.
401 Unauthorized
The server requires authentication. Add your API key as an Authorization header (Bearer token) or the specific header your server expects.
CORS error in browser console
This shouldn't happen since all connections are server-side. If you see CORS errors, please open a GitHub issue.
No tools listed
The server connected but returned an empty tools list. This is valid — the server may only expose resources or prompts, or it may require initialization parameters.
Free public servers to try
These servers are publicly accessible and require no authentication:
DeepWiki
No auth requiredQuery any GitHub repo's documentation
https://mcp.deepwiki.com/mcpMCP Registry
No auth requiredBrowse the official MCP server registry
https://registry.run.mcp.com.ai/mcp