openGym

openGym is a free, open-source gym and body-weight tracker that runs in the browser, on iPhone and Apple Watch, and on Android, with no account, no subscription, no ads, and no telemetry. You plan a weekly routine, log each workout with weights, reps and RIR, and watch a muscle map show where your volume went, what is still recovering, and what has gone untrained. Weights come pre-filled from your last session, a rest timer keeps the pace, and personal records are detected automatically across a library of more than 5,600 exercises.

The demo at opengym.ch/demo is the real app loaded with example data — nothing to install and nothing uploaded — and the same codebase builds a standalone app you can self-host with one Docker command or install as an Android APK. Imports cover Strong, Hevy, FitNotes and Apple Health weight exports, so switching from a paid tracker is a CSV export and a few taps.

How it was made is stated plainly in the README: "openGym is developed with Claude Code, Anthropic's coding agent. A large share of the code, tests and documentation is drafted in Claude Code sessions." The repository is under active development — its most recent push landed 2026-10-24 — and it carries 15,479 GitHub stars and more than 2,000 forks under the AGPL-3.0 licence.