Offline Voice Input (Android)

An offline, privacy-focused speech-to-text tool for Android, built with Rust. Tap the microphone on the keyboard you already use — your speech is transcribed entirely on-device and typed into any app. Also includes live subtitles and an optional dedicated voice keyboard.

Features

• Voice input in any app: Tap the microphone on the keyboard you already use (SwiftKey, etc.) or a website's voice search, and your speech is transcribed straight into the text field. The app registers as your device's speech-to-text provider.
• 100% offline & private: The Parakeet TDT model runs entirely on-device — no audio ever leaves your phone, and no network is required.
• Live Subtitles: Real-time captions for any audio/video playing on your device.
• Optional voice keyboard: A built-in keyboard you can switch to for voice input wherever you prefer it.
• Supported Languages: Bulgarian, Croatian, Czech, Danish, Dutch, English, Estonian, Finnish, French, German, Greek, Hungarian, Italian, Latvian, Lithuanian, Maltese, Polish, Portuguese, Romanian, Slovak, Slovenian, Spanish, Swedish, Russian, Ukrainian.
• Custom models: Import any transcribe.cpp GGUF model (Whisper, Nemotron streaming, Canary, more Parakeet variants, …) from a downloaded file — the app stays fully offline; downloads happen in your browser.
• Efficient native backend: All models run through transcribe.cpp (ggml), wrapped in a safe Rust core.

Screenshots

Usage

Voice input in any app (recommended)

1. Open Offline Voice Input once and grant the microphone permission. The home screen shows a Voice input status — green when you're ready to go.
2. In any app, tap the microphone on your keyboard (e.g. Microsoft SwiftKey) or the voice-search mic on a website. A compact panel slides up over the app you're in, you speak, and your words are inserted as text. Tap to stop — or enable Auto-stop after silence in the app's settings to have it stop by itself.

The app plugs into Android's speech-to-text in three ways, so it works with a wide range of keyboards and apps:

Tap Try voice input on the home screen to test the whole flow in one tap.

Keyboard notes (mic-key behavior verified against each keyboard's source and tested in the emulator):

• Microsoft SwiftKey (not open source) opens the compact voice panel directly, like website voice search does. If SwiftKey's own voice typing opens instead, go to SwiftKey Settings → Rich input → turn off Multi-modal voice typing.
• AnySoftKeyboard is the open-source way to get the panel: its mic key fires the standard speech intent as long as no voice keyboard is enabled on the system. (If one is enabled — ours or Google's — it switches to that instead.)
• HeliBoard, FlorisBoard, OpenBoard, Fossify Keyboard, Unexpected Keyboard: their mic key never opens the panel — it switches to the system voice input keyboard. Enable the Offline Voice Input keyboard (see below) and it opens automatically; its keyboard-switch key takes you back. FUTO Keyboard ships its own built-in voice input.
• Gboard: only uses Google's own voice typing, so it can't hand speech to this app at all.
• If Android shows a chooser, pick Offline Voice Input and tap Always. If another app always opens, clear its default in Settings → Apps.

Dedicated voice keyboard (optional)

Prefer voice input as its own keyboard? Enable the Offline Voice Input keyboard via Open Keyboard Settings on the home screen, switch to it from your keyboard switcher, then tap Tap to Record. By default the recording keeps running even if you switch apps or the keyboard closes (turn off Record in background in settings if you don't want that) — the text is inserted when you come back.

Live subtitles

Tap Start Live Subtitles and choose Share entire screen to get real-time, on-device captions for any audio or video playing on your device.

Advanced: skip the screen-capture dialog. Android shows a "Start recording or casting?" consent dialog every time subtitles start. You can pre-approve it once via adb — after that, subtitles start instantly and the setting survives reboots (USB debugging can be turned off again afterwards):

adb shell appops set --user 0 dev.notune.transcribe PROJECT_MEDIA allow

To undo it:

adb shell appops set --user 0 dev.notune.transcribe PROJECT_MEDIA default

This relies on the undocumented PROJECT_MEDIA app-op; on some OEM builds it may not work or may get reset by the system — the normal dialog remains the fallback. The same instructions are shown in-app under Skip the permission dialog (advanced).

Custom speech models

The built-in Parakeet model works out of the box. (The F-Droid build has no built-in model, since F-Droid builds everything from source: on first start, the app shows how to download the same model in your browser and import it. The F-Droid build is reproducible and carries the same signature as the GitHub releases, which also include it as …_fdroid.apk, so you can switch between the GitHub/Obtainium and F-Droid versions without reinstalling.) Under Manage speech models you can additionally import any transcribe.cpp GGUF model: download a .gguf file in your browser (the in-app Where to get models dialog lists direct links, e.g. a tiny 135 MB English-only Parakeet, the multilingual Nemotron 3.5 streaming model with punctuation, or Whisper large-v3-turbo), then import it via the system file picker and select it. The app itself needs no internet permission — model files are simply copied into the app's private storage. An optional language hint (e.g. en-US, or auto) can be set for imported models.

Prerequisites

Local Configuration

Create a local.properties file in the project root (this file is gitignored):

sdk.dir=/path/to/your/Android/Sdk

Gradle uses JAVA_HOME. If your default Java is not JDK 17 (Gradle 8.9 can't run on JDK 22+), point Gradle at one in your user-level ~/.gradle/gradle.properties instead of the project file:

org.gradle.java.home=/path/to/jdk17
# Examples:
#   /opt/android-studio/jbr          (Android Studio bundled JBR, if it is JDK 17/21)
#   /usr/lib/jvm/java-17-openjdk     (System JDK 17)

Building

The app has two build flavors: standard (GitHub releases, Google Play) bundles the Parakeet model, fdroid is the same app without it.

Debug APK

./gradlew assembleStandardDebug
# Output: app/build/outputs/apk/standard/debug/app-standard-debug.apk

Release APK

./gradlew assembleStandardRelease
# Output: app/build/outputs/apk/standard/release/app-standard-release.apk

Release AAB (Google Play)

./gradlew bundleStandardRelease
# Output: app/build/outputs/bundle/standardRelease/app-standard-release.aab

F-Droid flavor (no bundled model)

./gradlew assembleFdroidRelease
# Output: app/build/outputs/apk/fdroid/release/app-fdroid-release.apk

Signing

For release builds, place a release.keystore in the project root and set these environment variables:

export KEY_ALIAS=release
export KEY_PASS=yourpassword
export STORE_PASS=yourpassword

Model Assets

The built-in Parakeet TDT GGUF model (~485 MB) is automatically downloaded from HuggingFace during the first standard build via a Gradle task. The checksum is verified with SHA-256. No manual download is needed. fdroid builds never download it.

Project Structure

├── app/
│   └── src/main/
│       ├── AndroidManifest.xml
│       ├── java/dev/notune/transcribe/   # Android Java code
│       ├── res/                          # Resources (layouts, drawables, etc.)
│       ├── assets/                       # Model files (downloaded at build time)
│       └── jniLibs/                      # Native .so files (built by cargo-ndk)
├── src/                                  # Rust source code (cdylib)
├── Cargo.toml                            # Rust crate manifest
├── build.gradle.kts                      # Root Gradle config
├── app/build.gradle.kts                  # App module config (AGP 8.13.2)
├── settings.gradle.kts
├── gradle.properties
└── fastlane/metadata/android/            # F-Droid store listing

Acknowledgments

• Speech Model: Parakeet TDT 0.6b v3 by NVIDIA.
  • GGUF conversion by handy-computer.
  • Licensed under CC-BY 4.0.
• Inference Backend: transcribe.cpp by CJ Pais / Handy Computer.

License

MIT