MCP gateway · Built in Rust
Turn your existing APIs into secure MCP tools
api0 is a Rust-powered MCP gateway that turns your existing REST APIs into tools for Claude and other MCP-compatible clients. Connect Claude to your backend in under five minutes.
The usual friction
Glue code everywhere
Every new agent needs custom wrappers, auth handling and retry logic. It works until it doesn't.
Security is an afterthought
API keys end up in prompts, env files or agent memory, and the backend can’t tell which person an agent is acting for.
Performance and reliability matter
High-level runtimes introduce latency and failure modes you only discover in production.
One gateway. Any API. Any MCP client.
- Import an OpenAPI spec or describe endpoints in plain English: each becomes an MCP tool
- Works with Claude Desktop, Claude Code and any MCP-compatible client
- Each user approves once through OAuth, and every call carries who it is for
- Credits, access control and call logs on every tool call
- Gateway and backends written in Rust
“Book me a flight to Lisbon” → a real API call
What your backend receives
You choose how api0 authenticates to your backend. The credential lives in api0, never in the model, and is attached to every call.
See the whole architecture- A Google identity token that proves the call came from api0
- A fixed bearer token or custom headers
- OAuth client credentials
- Each person’s own secret
- Each person’s own account, connected once through OAuth
Production-grade by default
- The gateway and all its backends are written in Rust
- Backend credentials stay in api0; the model never sees them
- OAuth 2.1 with PKCE for Claude connectors
- Built and supported from Switzerland