Pierre is an open-source, multi-protocol fitness data API designed to securely integrate fitness data from various providers like Strava and Fitbit. It facilitates intelligent analysis by connecting this data to AI assistants such as Claude and ChatGPT, and other agents supporting the Model Context Protocol (MCP) and Agent-to-Agent (A2A) Protocol. The API offers comprehensive features including key management, rate limiting, OAuth integration, and real-time analytics, making it a robust solution for building AI-powered fitness applications.