Hosted, unauthorized MCP test server exposing a single tool, revealsecret. Use it to quickly verify your client can complete a real MCP round‑trip. Pure Go, no frameworks, easy to read and tweak the flow [1][2].

• Live site: https://mcptest.xyz
• Source: https://github.com/d33tah/mcptest

• Exposes one tool, revealsecret, that returns a short confirmation so you know an MCP call really worked [2].
• Built as a “pure” Go server using only the standard library (no frameworks) [1].
• Supports both:
  • OpenAI Playground (Flows) via an SSE endpoint [2]
  • OpenAPI-based clients (e.g., Open WebUI) via an OpenAPI spec URL [2]
• Authorization: set to None or use any token — it’s ignored [2].

• MCP SSE (for OpenAI Playground Flows):
  https://mcptest.xyz/sse [2]
• OpenAPI spec (for Open WebUI and other OpenAPI clients):
  https://mcptest.xyz/openapi.json [2]
• Tool operation exposed by the spec:
  POST https://mcptest.xyz/reveal_secret [2]

On success, revealsecret returns a small confirmation string; the current response body is: {"result":"no siemanko"} [1].

Using OpenAI Playground (Flows)

• Add a tool that talks MCP over HTTP/S via SSE.
• Endpoint: https://mcptest.xyz/sse
• Authorization: None or any token (ignored).
• Invoke revealsecret and verify you get a short success string [2].

Using OpenAPI (Open WebUI)

• Import the OpenAPI spec URL: https://mcptest.xyz/openapi.json
• Run the operation that maps to revealsecret:
  • POST /reveal_secret
• Authorization: None or any token (ignored).
• You should receive a small “secret” confirming the call executed [2].

cURL (hosted)

• POST https://mcptest.xyz/reveal_secret
• No auth required.

Example: curl -X POST https://mcptest.xyz/reveal_secret

Expected response: {"result":"no siemanko"} [1]

Prerequisites

• Go installed.

Build and run

• go run .
• The server starts on http://localhost:8000 [1].

Local endpoints

• SSE (Playground Flows): http://localhost:8000/sse [1]
• OpenAPI spec: http://localhost:8000/openapi.json [1]
• Tool: POST http://localhost:8000/reveal_secret → {"result":"no siemanko"} [1]
• Basic health: http://localhost:8000/ping [1]

• OpenAI: Company/products (e.g., Playground, Flows). Here, you configure a Flow tool that talks MCP over HTTP/S via SSE [2].
• OpenAPI: An API description format (formerly Swagger). Tools like Open WebUI can import an OpenAPI spec to call HTTP endpoints [2].

They differ by one letter, but they’re unrelated in this context. Use the SSE endpoint for OpenAI Playground Flows and the spec URL for OpenAPI-based clients [2].

Anything unexpected or have feedback? Please open a new issue: https://github.com/d33tah/mcptest/issues/new [2]

References:
[1] Server and handlers (pure Go, stdlib; port 8000; revealsecret returns "no siemanko")
[2] Hosted endpoints, usage notes, and OpenAI vs OpenAPI guidance as presented on the site