The Free MCP Sandbox

Test any Model Context Protocol (MCP) client in under a minute.

Endpoint

/mcp

Protocol Streamable HTTP

Authentication None

Available Tools — No Authentication Required

Use these to verify your connection, tool invocation, and JSON serialization.

identity

Returns server information. No parameters.

Response

MCP-SANDBOX canary 7Q9X-ZK42-VORTEX-PARSNIP

echo

Returns exactly what was sent.

Input

{"message": "Hello MCP", "repeat": 1}

Response

MCP-SANDBOX echo 4F7T-ECHO-START >>> Hello MCP <<< 4F7T-ECHO-END

URLs below are filled in from this page's address.

claude mcp add --transport http mcp-sandbox URL

{
  "mcpServers": {
    "mcp-sandbox": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "URL"]
    }
  }
}

⚠️ Use /mcp with no trailing slash — some clients drop the POST body across a 307 redirect.

Add a Bearer token to test authenticated tool calls. The auth_check tool verifies your token is being forwarded correctly.

This token is public and intended for integration testing only. public · test only

Authorization: Bearer mcp-sandbox-dev-C7H2-KPMERCHANT

Add --header "Authorization: Bearer <token>" to your MCP client config to use authenticated tools.