Codex ReaderTurn any book into a
synchronized readaloud
Bring your own ebooks and audiobooks. Codex aligns them automatically and gives you a seamless reading-and-listening experience on any device.
How it works
Three steps from your existing library to synchronized reading and listening.
Upload
Add your ebooks and audiobooks—formats you already own, from sources you already use.
Align
Codex synchronizes your audiobook narration with the ebook text, creating a readaloud.
Read & Listen
Text highlights as narration plays. Switch between reading and listening seamlessly.
Everything you need to read your way
Built for readers who want full control over their library.
Synced narration
Text highlights in real time as narration plays. Tap any sentence to jump there in the audio.
Offline & sync
Download books for offline reading. Your position, bookmarks, and progress sync across all your devices.
CarPlay
Browse your library and listen to your books while driving, with full CarPlay integration.
Make it yours
Choose your fonts, adjust text size, switch themes, and customize audio playback speed from 0.5× to 4×.
Bookmarks & highlights
Mark your place, highlight passages, and come back to them anytime.
Accessibility
Dynamic Type, OpenDyslexic, and high contrast support. Built to be readable by everyone.
Your library. Your rules.
Built for readers who care about ownership, privacy, and transparency.
No tracking
We don’t track your reading habits, sell your data, or profile your behavior. Your library is private.
No lock-in
Export your full library at any time—your files, annotations, and reading progress. Always portable.
Open source
Codex Reader is built on the Storyteller platform. Inspect the code, self-host it, or contribute.
Free during beta
The Codex Reader app is free—and always will be.
Beta
Free
All features included while we're in beta
- ✓Unlimited uploads and alignments
- ✓Cloud sync across all devices
- ✓Full library export at any time
Codex Cloud is an optional service for cloud alignment and sync. It's free during the beta, with a subscription plan after launch.
Questions
Yes. The Codex Reader app is free to download and use. Optional upgrades are available for power users who want more from their library.
Codex Cloud is the service that powers cloud alignment and device sync. Upload your ebooks and audiobooks, and Codex Cloud aligns them into synchronized readalouds you can enjoy on any device. During the beta, all Codex Cloud features are free.
Your books and reading data remain accessible for at least 6 months after cancellation. You can export your full library at any time, including annotations and reading progress. We will never delete your data without notice.
Yes. Codex Reader is built on the open-source Storyteller platform, which you can run on your own hardware. Self-hosting gives you full control over your data and alignment pipeline.
iOS is the primary platform during the beta. Android support is planned for a future release.
EPUB for ebooks and M4B or MP3 for audiobooks. Upload both an ebook and its matching audiobook, and Codex will align them into a synchronized readaloud.