Kompact

Kompact is an open-source Android app written in Kotlin with Jetpack Compose that compresses images (JPEG, PNG, WebP) quickly and transparently. Official builds are produced and signed by the maintainer to keep a single line of trust that stays compliant with F-Droid and Google Play policies.

Key Features

• Multi-selection of images through the Storage Access Framework.
• Fully configurable compression parameters (quality, max size, output format).
• Result cards summarize original vs compressed size and the status of each operation.
• Modern Material 3 UI with light/dark support.
• Automatic export to the Pictures/Kompact directory with the option to pick any other destination.
• Side-by-side preview of source/output with synchronized quality and target size controls.

Note: PDF documents, audio tracks, and video files are not supported yet. They remain on the roadmap and will arrive in future releases once the image workflow is fully battle-tested.

Design

• FDroid-inspired palette with emerald primary (#1C8F62), denim secondary (#2F5978), and orange accent (#B55300) for a clean, opinionated look.
• AA contrast maintained between text/icons and both light/dark surfaces for accessible viewing.

Requirements

• Android Studio Ladybug or newer.
• Android Gradle Plugin 8.5+, Gradle 8.7.
• JDK 21 (recommended) or JDK 17 configured through JAVA_HOME.
• Android SDK 35, minSdk 24.

Quick start

# from the project root
./gradlew assembleDebug
./gradlew test
./gradlew assembleRelease

Artifacts must be signed with your own keys when testing private builds because production signing happens exclusively on the maintainer release workstation.

Project structure

• app/src/main/java/com/kompact/data contains the local repository and compression logic.
• app/src/main/java/com/kompact/ui hosts the ViewModel and main composables.
• app/src/main/java/com/kompact/model exposes shared domain models.
• app/src/main/java/com/kompact/util keeps reusable helpers.

Distribution policy

• The codebase contains no proprietary services, so it remains eligible for F-Droid and other FLOSS catalogs.
• Release builds stay unsigned inside the repository to let F-Droid reproduce them with its keys.
• Google Play specific assets (screenshots, policy text, signing artifacts) are curated by the maintainer, and production uploads happen from the same release workstation.
• For third-party forks, change the application ID and sign with independent keys to avoid name collisions.

docs/PUBLISHING.md tracks the release checklist shared with platform maintainers, focusing on the steps reviewers need for compliance checks.

Release governance

• Tags are created only by the maintainer after running the full QA pass.
• Official packages are distributed exclusively through the maintainer-operated channels (Git tags, eventual F-Droid entry, Google Play listing).
• Community contributions are welcome, but merging or publishing decisions always stay under upstream control to preserve a single trust source.

License

Kompact is distributed under the GNU Affero General Public License v3.0 only. Refer to LICENSE for details and always include a link to the source when redistributing binaries or forks.