Callio

Callio is an integration layer designed to connect AI agents to real-world services through a unified, API-first interface. It centralizes access to 50+ third-party APIs and nearly 400 endpoints, exposing them via a single key and consistent protocol. The primary purpose of Callio is to simplify how agents interact with external systems, whether through the Model Context Protocol (MCP) or a REST proxy, so developers can focus on agent logic instead of integration plumbing.

Under the hood, Callio normalizes authentication, rate limiting, and request/response formats across diverse APIs, reducing the need for custom wrappers and one-off connectors. It provides a catalog of ready-to-use integrations (e.g., communication, data, productivity, and developer tools) that can be called directly from AI agents. The MCP support lets LLM-based agents discover and use tools dynamically, while the REST proxy makes it easy to integrate from any environment that can issue HTTP requests. Centralized configuration and observability help teams manage keys, monitor usage, and debug agent-to-API interactions more efficiently.