Callio is an API marketplace and gateway built specifically for AI agents. It enables agents to discover, authenticate, and call any API through a single unified interface, eliminating the need to manage individual API keys or handle different authentication flows.

Callio provides access to 50+ APIs across categories including search, payments, email, data, messaging, analytics, cloud services, identity verification, social platforms, AI/ML models, developer tools, and storage. The platform handles authentication injection, usage tracking, billing, rate limits, and routing automatically. It works with Claude Code, Cursor, Antigravity, LangChain, CrewAI, and any MCP-compatible tool.

The platform operates through a simple three-step process: connect once with a single API key, discover APIs through browsing or agent search, and execute calls through one unified endpoint. Callio provides a unified proxy endpoint where users simply change the API slug to access different services. It also offers an MCP server that gives AI agents instant access to all APIs using natural language.

Benefits include faster shipping times by eliminating infrastructure work, reduced complexity by managing multiple APIs through one interface, and instant API discovery for agents. Use cases include giving AI agents real-world capabilities like web search, email sending, payment processing, and data enrichment.

The product targets AI developers building agent workflows, API providers seeking distribution to AI agents, and startups needing to ship quickly without infrastructure overhead. It integrates with popular AI development tools and frameworks through MCP compatibility and REST proxy endpoints.