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OnlineCompiler.io MCP Server

by onlinecompiler Your server? Claim it
answering

OnlineCompiler.io is answering right now. Last checked 8 min ago. Last commit 7 Nov 2026.

Run Python, Java, C, C++, C#, Go, Rust and 39 more languages, each run in a fresh, offline sandbox.

Uptime history 22 days of history
22 days agonow
100.0%
Uptime 24h
91 of 91 checks
—
Tools
hidden behind auth
68 ms
Response time
average over 24h
0
Stars
last commit 7 Nov 2026

Nothing serious here today

Today is the operative word: we check OnlineCompiler.io every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Three servers free · no card

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 8 min ago.

run in your terminal
claude mcp add compiler --transport http https://api.onlinecompiler.io/mcp
Settings → Connectors → Add custom connector, then paste this address
https://api.onlinecompiler.io/mcp
~/.codex/config.toml
[mcp_servers.compiler]
url = "https://api.onlinecompiler.io/mcp"
.cursor/mcp.json
{
  "mcpServers": {
    "compiler": {
      "url": "https://api.onlinecompiler.io/mcp"
    }
  }
}
.vscode/mcp.json
{
  "servers": {
    "compiler": {
      "type": "http",
      "url": "https://api.onlinecompiler.io/mcp"
    }
  }
}

This endpoint answered with an authorization challenge. The server is running, and it signs you in through your browser: there is no API key to paste.

Endpoints

URLTransportStateLatencyChecked
https://api.onlinecompiler.io/mcp streamable-http sign-in 37 ms 8 min ago

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OnlineCompiler.io — questions

Answers built from our own checks of this server.

Why is there no tool list for OnlineCompiler.io?
The server answered our handshake with an authorization challenge, so it is running — but it will not describe its tools to an anonymous client. To see them you need to connect with your own credentials. We record it as alive, not as broken: 100.0% of checks in the last 24 hours got a reply.
Is OnlineCompiler.io working right now?
We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 68 ms. The bar chart above shows every period we have measured.
How do I connect OnlineCompiler.io?
Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address. You sign in through your browser once and the client keeps the session: no key to copy, and it refuses anonymous clients.
How do you sign in to OnlineCompiler.io?
No API key is involved. OnlineCompiler.io answers our knock with an OAuth challenge, so you authorise it once in your browser and the client keeps the session. That is also why we see no tool list: it will not describe itself to an anonymous client, and that is the server working as intended, not a fault.
How fast is OnlineCompiler.io?
It answers our handshake in 68 ms on average, which is faster than 99% of all working MCP servers we measure. That puts it in the quick quarter of the ecosystem. The comparison comes from our own checks across the whole registry, every 15 minutes.
Is OnlineCompiler.io open source?
The code is open source: it is published under the MIT licence, written in Python and 0 stars on GitHub. The licence covers the code in the repository, not the hosted service at api.onlinecompiler.io, which runs on its operator's own terms.