Callio

Callio is a unified API gateway for AI agents. Instead of managing auth, rate limits, and keys for every API your agent uses, connect them all through one proxy. Works with Claude Code, Cursor, Antigravity, and any MCP-compatible tool. Browse APIs, generate a single Callio key, and start calling — we handle auth injection, usage tracking, and billing. Free tier included. One key, every API, zero config