Aloud

An offline Android app that reads your documents aloud with a natural, on-device AI voice. Import a file (PDF, Markdown, or Word), tap anywhere in the text, and it reads from there — fully offline, with the sentence being spoken highlighted as it plays. Audio is cached per document and narration profile, so matching audio can be reused on reopen.

How it works

• Platform: React Native (Expo SDK 56, TypeScript), Android, portrait.
• Voice: on-device text-to-speech using Supertonic (ONNX) via onnxruntime-react-native — nothing is sent to the cloud, no audio leaves the device. The selected voice model (about 263 MB for Supertonic 2 or 398 MB for Supertonic 3) is downloaded during onboarding and then works fully offline.
• PDF + text: PDFs are extracted page-by-page in a hidden local PDF.js WebView. The resulting canonical text and character offsets drive a reflowed native reader, tap-to-start, highlighting, and resume position. Markdown and DOCX are extracted directly in JavaScript.
• Other pieces: expo-audio (playback), expo-file-system (model + audio cache), a small Android MediaCodec module (AAC/M4A encoding and audiobook concatenation), react-native-svg (icons), and bundled fonts (Newsreader, DM Sans, JetBrains Mono).
• UI: a centralised design-token theme (light/dark), a shared component library, and screens for the Library, Reader, Settings, and first-run model download.

Source lives under src/ (components/, screens/, navigation/, theme/, types/, and supertonic/ — the TTS engine). See coderules.md for the code conventions.

How to launch

Requirements: Node.js, the Android SDK + adb, and an Android phone with USB debugging enabled.

npm install

Dev run (build, install, and start — easiest):

npx expo run:android

Fast re-runs (app already installed, no native changes):

adb reverse tcp:8081 tcp:8081
npx expo start --dev-client --host localhost

then press a to open it on the phone. (--host localhost + adb reverse routes through the USB/wireless bridge and avoids the firewall blocking Wi-Fi port 8081.)

Without a cable: pair the phone once via Settings → Developer options → Wireless debugging (adb pair … then adb connect …), then use the same commands above.

Standalone (no computer, fully offline): build a release APK with the JS bundled in:

npx expo run:android --variant release

Output: android/app/build/outputs/apk/release/app-release.apk — install it on any phone via "allow unknown sources" and launch from the home screen.

Onboarding needs internet once to download the selected voice model; everything after that is offline.