Articles

What's new in freddy: week of Jun 29, 2026

freddy is now on Android with Health Connect, queries work across more AI clients, Suunto workout calories are fixed, and morning data lands on time.

How Garmin, WHOOP, Oura, Polar, Ultrahuman, Withings, Amazfit, and Eight Sleep measure HRV

One body, seven wearables, HRV numbers from 38 to 95. A deep look at RMSSD vs SDNN and how WHOOP, Oura, Garmin, Fitbit, Polar, Ultrahuman, Apple, and Withings each derive their figure.

What's new in freddy: week of June 22, 2026

freddy is now an official ChatGPT app, Ultrahuman is generally available, intervals.icu workouts include per-lap detail, and the dashboard shows each source's sync status more clearly.

freddy is now an official ChatGPT app

freddy is now in the ChatGPT app directory. Connect it in a couple of clicks and ask ChatGPT about your sleep, training, and recovery using your own devices.

What's new in freddy: week of June 8, 2026

Two new sources (Runalyze and Lyfta), full Garmin history import from your data export, pause and resume for any connection, and a connected-devices view.

What's new in freddy: week of June 1, 2026

Garmin and Airthings reach general availability, deeper Polar data with heart-rate zones, richer Garmin activities, a redesigned dashboard, and the new freddy CLI.

How to give an AI agent access to your health data from the command line

A command-line tool lets a headless AI agent sign in, connect your wearables, and read your sleep, recovery, and training data, without you building an OAuth integration by hand.

What's new in freddy: week of May 25, 2026

Ultrahuman joins in beta, Wahoo and Concept2 reach general availability, a refreshed brand, and connections that stop dropping on a brief hiccup.

What's new in freddy: week of May 18, 2026

Multi-device tracking that no longer loses data, more reliable Garmin history, and cleaner account disconnects.

Polar versus Oura for everyday recovery tracking

A head-to-head comparison of Polar Vantage V3 and Oura Ring Gen 4 for recovery tracking: form factor, cost model, Nightly Recharge vs Readiness Score, and which to buy.

What's new in freddy: week of May 11, 2026

Three new data sources (Garmin, Wahoo, Concept2), a simpler email-code sign in, full-history queries, and cleaner Perplexity support.

Best wearable APIs for AI agents: a developer's guide

Practical comparison of the major wearable APIs for developers building AI tooling: rate limits, data depth, OAuth quirks, and which APIs make AI integration painless versus painful.

The complete guide to connecting wearable data to AI

What it takes to ask AI assistants like Claude or ChatGPT about your sleep, recovery, workouts, and HRV from any wearable. The pieces that have to fit together, and where each piece comes from.

HRV across wearables: how to actually compare what your devices report

Different wearables report HRV differently. Here's why your Oura number doesn't match your WHOOP number, what units to expect from each device, and how to compare across them anyway.

Oura vs WHOOP for sleep tracking: which one should you actually buy?

Honest comparison of Oura and WHOOP for sleep tracking. Form factor, battery, accuracy, what each one's API exposes, and which fits which kind of user.

6 best personal health MCP servers in 2026

An honest ranking of MCP servers (and the adjacent first-party connectors) that link your wearables and health data to AI assistants like Claude, ChatGPT, and Cursor.