Audiobookify: Free iPhone EPUB Reader with Local CoreML Text-to-Speech
A developer has introduced Audiobookify, a free iOS EPUB reader featuring highly optimized, local offline text-to-speech (TTS). The app utilizes custom CoreML-converted models like Kokoro and Supertonic 3 to deliver high-quality narration directly on-device. This project showcases the practical application of edge AI on mobile devices, proving that lightweight TTS models can run efficiently on-device without draining battery or causing thermal issues. It offers a privacy-focused, offline alternative to cloud-based text-to-speech services. Currently available via TestFlight, Audiobookify does not support PDF files yet and is not open-source. The developer hand-optimized the models for iOS and plans to support models from Kyuutai in the future.
## BACKGROUND
CoreML is Apple's machine learning framework that allows developers to integrate trained models into iOS apps, leveraging the Apple Neural Engine for fast, on-device execution. Kokoro is a lightweight, open-weight TTS model with 82 million parameters designed to deliver natural-sounding speech efficiently.