OPEN SOURCE

An open-source workout tracker with no server to host

Last updated: 20 October 2026 · By vplsdev, the developer

Ischys is a free, open-source workout tracker and gym log for iPhone and Apple Watch. Its entire source code is public under the MIT licence, and it needs no server, no account and no subscription. 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.

Why there is no server

Many open-source workout trackers are self-hosted: a web app you install on your own server or home computer, then open from your phone. That gives you control, and it also gives you a server to keep running and updated. Ischys takes the other route. The app is the whole system, installed from the App Store like any other, with your training log in a database on the phone. There is nothing to host, and it works in a gym with no signal.

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.

What to check in any open-source workout tracker

The licence. An OSI-approved licence such as MIT, GPL or AGPL means you can read, build and fork the code. "Source available" is not the same thing.
Whether the shipped app matches the source. Ischys keeps the iPhone, Watch, Android and Wear OS apps in one public repository, and the store builds are made from it. You can also build and install it yourself, as described above.
Where your data lives. On your phone, on a server you run, or on the developer's cloud. Ischys keeps it on the phone.
How you get it out. Ischys exports your workout history as CSV or JSON, and imports a workout CSV from other apps.
Whether it is maintained. Check the commit history and the issue tracker on GitHub.

Questions

Is there an open-source workout tracker for iPhone?

Yes. Ischys is a free, open-source workout tracker for iPhone with an Apple Watch app and a Lock Screen Live Activity. The full source is on GitHub under the MIT licence and the app is on the App Store.

Do I need to run a server to use an open-source workout tracker?

Not with Ischys. Many open-source trackers are self-hosted web apps that you install on your own server. Ischys is an ordinary phone app with no backend: install it from the App Store and your training log lives on your phone.

Is Ischys really free?

Yes. There is no subscription, no paid tier, no in-app purchases and no ads. Every feature, including routines, charts, personal records and the Apple Watch app, is in the free app.

Is there an open-source workout tracker for Android?

Ischys also runs on Android with a Wear OS companion, built from the same source. The Android apps are in closed testing on Google Play and are not publicly listed yet.

Can I check what the app does with my data?

Yes. The full source is public, so you can read it and confirm there is no backend, no account system and no analytics, advertising or crash-reporting code.

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