zerouter-mcp

AI API gateway MCP for Claude, GPT, Gemini, Grok and Kimi via Zerouter.

zerouter-mcp connects Claude Desktop, Cursor, Claude Code and other MCP clients to Zerouter, an OpenAI-compatible AI API gateway. With one API key you can chat with any supported model, compare answers side by side, or look up API pricing per 1M tokens, without leaving your editor.

Why Zerouter

• One API key for Claude, GPT, Gemini, Grok and Kimi. The same sk- key routes to every model. Zerouter exposes Anthropic-compatible and OpenAI-compatible endpoints, so it works with Claude Code, Codex and Cursor—change the base URL and keep your existing clients.

• API pricing you can check in chat. Claude Opus 5.5 on Zerouter is $1.16 input / $5.81 output per 1M tokens (Anthropic list price $4 / $20). Live rates for GPT, Gemini, Grok and Kimi are on the Zerouter pricing page.

• Compare models before you commit. Send one prompt to 2–4 models in parallel and get each answer with token usage, latency and estimated cost.

• Stable routing, real models. The model ID you send is the model that runs and the one you're billed for. Prompts aren't rewritten and models aren't swapped.

• Host unused subscription quota. If you have an official AI account with capacity you don't use, the Zerouter provider program routes paid traffic to it and pays you the larger share of each request, currently about 80%, in USDC.

Related MCP server: Adaptive LLM Gateway

What it does

You don't have to think about API formats. chat sends each request to the right Zerouter endpoint for you:

• Claude and Kimi go to POST /v1/messages (Anthropic format)

• GPT, Codex and Grok go to POST /v1/responses (OpenAI Responses)

• Gemini and the compatible channels (Qwen/Dashscope and others) go to POST /v1/chat/completions

If you need to, you can override this with the endpoint argument.

Get a key

1. Sign in at zerouter.ai and open the dashboard.

2. Create an API key. Keys start with sk- and work for every model.

3. Put it in the ZEROUTER_API_KEY environment variable, as in the configs below.

See the pricing page for current API pricing and the quickstart for setup details.

Setup

You need Node.js 18 or newer with npm 10 or newer (bundled with current Node 18/20/22 releases). npx fetches the server straight from GitHub, builds it once and runs it. The first start takes up to a minute while it installs; later starts use the npx cache.

The package isn't published to npm, so use github:ZerouterAI/zerouter-mcp as shown below (not zerouter-mcp). Prefer not to use npx? See Other ways to install.

Claude Desktop

Edit claude_desktop_config.json. On macOS it's in ~/Library/Application Support/Claude/ and on Windows in %APPDATA%\Claude\:

{
  "mcpServers": {
    "zerouter": {
      "command": "npx",
      "args": ["-y", "github:ZerouterAI/zerouter-mcp"],
      "env": {
        "ZEROUTER_API_KEY": "sk-xxxx"
      }
    }
  }
}

Restart Claude Desktop afterwards.

Cursor

Add this to ~/.cursor/mcp.json for all projects, or to .cursor/mcp.json in a single project:

{
  "mcpServers": {
    "zerouter": {
      "command": "npx",
      "args": ["-y", "github:ZerouterAI/zerouter-mcp"],
      "env": {
        "ZEROUTER_API_KEY": "sk-xxxx"
      }
    }
  }
}

Claude Code

claude mcp add zerouter --env ZEROUTER_API_KEY=sk-xxxx -- npx -y github:ZerouterAI/zerouter-mcp

Add --scope user to make it available in every project.

Other ways to install

MCPB bundle (Claude Desktop one-click). Download zerouter-mcp-0.1.0.mcpb from the latest release and open it, or drag it into Claude Desktop under Settings → Extensions. Claude Desktop asks for your API key; no Node.js setup needed.

Clone and build. Works with any MCP client that can run a local command:

git clone https://github.com/ZerouterAI/zerouter-mcp.git
cd zerouter-mcp
npm install        # also builds dist/ via the prepare script

Then point your client at the built file, using the absolute path on your machine:

{
  "mcpServers": {
    "zerouter": {
      "command": "node",
      "args": ["/absolute/path/to/zerouter-mcp/dist/index.js"],
      "env": {
        "ZEROUTER_API_KEY": "sk-xxxx"
      }
    }
  }
}

For Claude Code: claude mcp add zerouter --env ZEROUTER_API_KEY=sk-xxxx -- node /absolute/path/to/zerouter-mcp/dist/index.js

Docker

docker build -t zerouter-mcp .
docker run -i --rm -e ZEROUTER_API_KEY=sk-xxxx zerouter-mcp

Environment variables

If no key is set, get_pricing and list_models still work. chat and compare_models return a clear error that tells you where to get a key.

Example prompts

• "What does Claude Opus 5.5 cost on Zerouter compared with the official API pricing?"

• "Ask gemini-3.8-flash to summarise this file."

• "Compare claude-sonnet-5-5, gpt-6-sol and grok-4.6 on this regex question and tell me which answer is right."

• "Which models on Zerouter cost less than $0.50 per million input tokens?"

Development

git clone https://github.com/ZerouterAI/zerouter-mcp.git
cd zerouter-mcp
npm install       # runs the build through the prepare script
npm test          # spawns the server over stdio and calls every tool (no key needed)
npx @modelcontextprotocol/inspector node dist/index.js

Links

• Start here: zerouter.ai — get a key and see how it works

• Model list: zerouter.ai/models

• API pricing: zerouter.ai/pricing

• Docs: zerouter.ai/docs

• Provider program: provider.zerouter.ai/docs

• Issues: github.com/ZerouterAI/zerouter-mcp/issues

License

MIT. Built by the Zerouter team.