OPEN SOURCE

An open-source workout tracker

Last updated: 13 October 2026

Ischys is a free strength-training log for iPhone whose entire source code is public under the MIT licence. Android and Wear OS versions are in testing and not public yet.

What is open

Everything that ships. The iPhone app, the Apple Watch app, the Lock Screen Live Activity and the Android and Wear OS apps live in one repository at github.com/ischys-app/Ischys. The MIT licence lets you read it, build it, change it and redistribute it. The bundled exercise illustrations (CC BY-SA 4.0) and fonts (SIL OFL) keep their own licences; the README has the details.

Why that matters for a training log

A privacy policy asks for trust. Here you can check the claim. Ischys has no backend and no account system, and it contains no analytics, advertising or crash-reporting code. Your workouts are rows in a SQLite database on your phone, and every statistic (volume, estimated one-rep max, personal records, streaks, charts) is computed on the device.

The app does not send your data anywhere. The only network access is what you ask for: it opens this website or GitHub in your browser when you tap those links in Settings, and if you attach a demo to an exercise by pasting a web address, the video or image loads from that address. iOS may also show its standard App Store rating prompt, which Apple handles.

What it does

Logs strength workouts: weight and reps, warm-up, drop and failure sets, and a rest timer.
Routines that prefill each set from your last session.
Personal records detected when you finish: best set, estimated one-rep max, best volume and most reps, with history and charts for every exercise.
An Apple Watch companion, a Lock Screen Live Activity and optional Apple Health.
A 736-exercise catalogue bundled in the app, so it works with no connection.
Import from a workout CSV; export your workout history as CSV or JSON.

How it is built

A React Native and Expo app written in TypeScript, with a local SQLite database. The training logic is plain, tested TypeScript in frontend/src/domain. The Apple Watch app and the Live Activity are native Swift targets in the same project.

Build it yourself

You need macOS with Xcode and a free Apple developer account to sign the app onto your own iPhone.

git clone https://github.com/ischys-app/Ischys.git
cd Ischys/frontend
npm install
npx expo run:ios --device

Drop --device to run it in the iOS Simulator. The README covers the Android build.

Why it is free

Ischys is built by one developer who wanted a tracker that sent data to no one and lacked nothing. With no server to run there is nothing to charge for, so there is no paid tier and every feature is in the free app.

Take part

Bug reports and ideas go to GitHub issues, and the contributing guide explains how to send a change. If you are weighing Ischys against other trackers, there is a sourced comparison.

Download on the App Store Source on GitHub Back to the overview