Polar Health Data (self-hosted) MCP server

polar-flow-server

Self-hosted health analytics for Polar devices — own your data, analyze it against your own baselines, and let your AI assistant read it.

Full Documentation · MCP Server · Integration Guide · API Reference

What This Does

Your watch knows more about you than you do — and Polar's API only lets you see the last 28-30 days of it. This server syncs everything, keeps it forever, and turns it into answers:

1. Syncs all 13 Polar API endpoints automatically — sleep, HRV, activity, workouts, SpO2, ECG, skin temperature, the lot
2. Stores everything in PostgreSQL. Your data, your server, no cloud between you and it
3. Computes personal baselines (rolling averages, IQR anomaly bounds) so "is this normal?" means normal for you
4. Ships a built-in MCP server with OAuth sign-in — ask Claude "should I train hard today?" and it answers from your overnight HRV vs your baseline
5. Admin dashboard (HTMX), REST API, per-user API keys, multi-user ready

Ask Your AI About Your Body (MCP)

A built-in Model Context Protocol server — protocol revision 2026-07-28, streamable HTTP — runs inside the main server at /mcp. Ten curated tools cover the one-shot health assessment, sleep, recovery, activity, workouts, seven biosensing streams, personal baselines, patterns/anomalies, and sync control.

In clients that render MCP Apps (claude.ai, Claude Desktop, VS Code), asking "how am I doing?" draws an actual card in the conversation:

Connecting is a sign-in, not a paste. With BASEURL set, the server is its own OAuth 2.1 authorization server: add https://your-server/mcp as a custom connector in Claude Desktop or claude.ai, click Connect, log in on your* server, approve the consent screen. Tokens are user-scoped, expire hourly, refresh automatically, and every connected app is revocable from Settings. API keys still work for headless clients:

claude mcp add polar-health https://your-server.example.com/mcp \
  --transport http \
  --header "X-API-Key: pfk_your_key_here"

Full setup in the MCP docs.

Architecture

Polar API → polar-flow SDK → Sync Service → PostgreSQL
                                                  ↓
                                           Admin Dashboard (HTMX)
                                                  ↓
                                             REST API

Stack:

• Litestar (async web framework)
• SQLAlchemy 2.0 (async ORM)
• PostgreSQL
• HTMX + Tailwind (admin UI)
• polar-flow SDK v1.5.0

Don't fancy running a server? A hosted version is in the works — join the waitlist. Self-hosting stays free forever.

Quick Start

Option 1: Docker (Recommended)

Shortened. The full README is on GitHub.