APK Builder

A no-code Android app builder that runs entirely on the device. Users pick a template, customise it (colours, header, tabs, top/bottom bars, window size, icon, splash, audio), preview the result, and tap Build APK to generate an installable APK with a selectable ABI target (32-bit / 64-bit / Universal).

The APK Builder app itself supports armeabi-v7a, arm64-v8a, x86, and x86_64, so it runs on every Android phone from 5.0 (Lollipop) up.

How to build

Android Studio

1. File → Open… and pick the android-apk-builder/ folder.
2. Let Gradle sync (Android Gradle Plugin 8.2.2, Kotlin 1.9.22, Compose).
3. Click Run ▶.

AIDE (on-device)

1. Copy the android-apk-builder/ folder to your phone.
2. Open AIDE, choose Open existing project and select the folder.
3. AIDE will detect the Gradle structure; tap Run / Build APK.

AIDE Pro is required for Kotlin + Gradle projects. If you don't have AIDE Pro, open the project in Android Studio first, run a debug build to populate app/build/outputs/apk/, then copy that APK to your device.

Project layout

android-apk-builder/
├── settings.gradle / build.gradle / gradle.properties
├── gradle/wrapper/gradle-wrapper.properties
├── app/
│   ├── build.gradle              # AGP 8.2.2, Compose, apksig, Bouncy Castle
│   ├── proguard-rules.pro
│   └── src/main/
│       ├── AndroidManifest.xml
│       ├── res/                  # themes, colours, launcher icon, file_paths
│       ├── assets/templates/     # per-template manifest.json + (your) template.apk
│       └── java/com/apkbuilder/app/
│           ├── MainActivity.kt
│           ├── theme/Theme.kt
│           ├── model/            # Template, ProjectConfig, AbiTarget
│           ├── builder/          # ApkAssembler, ApkInstaller, KeystoreManager, ProjectStore
│           └── ui/               # AppRoot + Templates / Editor / Preview / Build / Projects / Settings
└── template-sources/README.md    # how to author a template APK

How the on-device build actually works

Real on-device Java→DEX compilation is not possible from a sandboxed Android app — there is no JDK, no aapt2, and SELinux blocks dex2oat from arbitrary paths. The honest, working approach (used by Sketchware, Apk Editor, etc.) is template patching:

1. Each template is a pre-compiled APK shipped in assets/templates/<id>/template.apk. Its runtime reads assets/config.json and assets/branding/* to render the user's chosen colours, text, images, and audio.
2. When the user taps Build APK, ApkAssembler:
   • copies the template APK to the cache;
   • streams its zip entries into a new APK, replacing assets/config.json and any branding files with the user's customisations, and dropping lib/<abi>/*.so entries that don't match the chosen 32/64-bit target;
   • signs the result with a self-signed key (v1 + v2 schemes for maximum install compatibility) generated and persisted by KeystoreManager.
3. The output APK is written to filesDir/builds/ and handed to the system installer via a FileProvider.

What you (the developer) need to add once

The repo ships one manifest.json per template but no template.apk binary — you build those yourself in Android Studio once, then drop them into app/src/main/assets/templates/<id>/template.apk. See template-sources/README.md for the contract every template runtime must follow (assets/config.json, optional assets/branding/*).

After that one-time step the project is fully self-contained: end users install the APK Builder, pick a template, customise, build — no server, no extra setup.

Adding more templates

1. Build a new template APK that follows the contract in template-sources/README.md.
2. Drop it at app/src/main/assets/templates/<your-id>/template.apk.
3. Add a matching entry to app/src/main/assets/templates/manifest.json and to Template.BUILT_IN in model/Template.kt.

The drag-and-drop editor and the build pipeline pick the new template up automatically.