GymLogger

GymLogger is a minimalist, 100% private, open-source weightlifting logger.

It's a fork of GymLoga by Michael Bosse, redesigned around Material You (inspired by Book Story) with a true-black AMOLED dark theme, and reworked so your log saves itself — there is no save button.

Features

• Auto-saving log: Everything you add to a day is written instantly. Add an exercise, a set, or a note and it's already saved — no "Save" button, no lost sessions.
• Blazing fast entry: Log your sets with simple shorthand like 135*5*2 or 20*10 (weight * reps * sets).
• Automatic PR tracking: The app identifies your Personal Records (PRs) as you log.
• Strength analytics: View your exercise history and estimated One Rep Max (1RM) progress.
• Material You: Dynamic color on Android 12+ with a tasteful fallback palette, on a pure-black AMOLED surface.
• Privacy first: No tracking, no ads, no cloud syncing. Your data never leaves your device.
• Modern native feel: Built with Kotlin and Jetpack Compose (Material 3).

Building from source

The repository ships a Nix shell that provides a pinned JDK 17 + Android SDK, so no global Android tooling is required:

nix-shell --run './gradlew :app:assembleDebug'

Run the unit tests with:

nix-shell --run './gradlew :app:testDebugUnitTest'

The debug APK is generated at app/build/outputs/apk/debug/app-debug.apk.

If you already have a local Android SDK (ANDROID_HOME set, build-tools 36.0.0, platform 36), the standard ./gradlew assembleDebug works too.

Testing / profiling

emulator.nix provisions a headless Android emulator (JDK 17 + SDK 34 + an x86_64 system image) so the app can be driven and profiled without a physical device. scripts/emulator.sh wraps the lifecycle:

# boot a KVM-accelerated emulator in the background, then wait for it
nix-shell emulator.nix --run './scripts/emulator.sh boot' &
nix-shell emulator.nix --run './scripts/emulator.sh wait'

# install, launch, screenshot
nix-shell emulator.nix --run './scripts/emulator.sh install'
nix-shell emulator.nix --run './scripts/emulator.sh launch'
nix-shell emulator.nix --run './scripts/emulator.sh shot today'   # -> .emulator/shots/today.png

nix-shell emulator.nix --run './scripts/emulator.sh down'         # stop it

scripts/jank-test.sh drives a fixed typing workload and prints the gfxinfo summary. Note the bundled emulator renders with SwiftShader (software GL), so frame-level jank numbers are dominated by the renderer and are not representative of real hardware. To measure the auto-save cost specifically, the most reliable signal is render-independent — e.g. counting DataStore writes with inotifyd files/datastore during a typing burst (debounced saves collapse a burst of keystrokes into a single write).

Install / self-hosted F-Droid repo

Signed builds are published to a custom F-Droid repository hosted entirely on GitHub (Actions + Pages). Add this to your F-Droid client for automatic updates:

https://criickt.github.io/GymLogger/fdroid/repo

Tagging v* builds a signed APK, regenerates the repo, and cuts a GitHub Release. Setup and release steps are in docs/FDROID.md.

License

This project is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0) or later. See the AGPL-3.0-or-later file for details. As a fork, it preserves the original copyright and license of GymLoga.