products / PROJECT NOTE / 2026

OfflineTTS: long-form speech generation, entirely on your phone

A Kotlin Android app for private, quota-free narration in 10 languages and 11 locale options.

Kotlin · Jetpack Compose · ONNX Runtime · Piper · Kokoro

OfflineTTS runs speech generation on-device after the voice model is downloaded. I built and published the Android application with Kotlin, Jetpack Compose, ONNX Runtime, Piper, Kokoro and eSpeak NG.

Language-aware phonemization and chunked ONNX inference support long scripts without a character quota. I tested inputs with more than 70,000 characters. The resume records support for 10 languages with 11 locale options.

The app includes downloadable and deletable voice models, background conversion, audio preview, saving and sharing. It reached more than 100 organic Google Play installs.