Hi, I made a thing! This is by far the most work I've ever sunk into a side project; I've been working on this thing for over two years, and I'm super proud of it, even though there's still a lot more to do!
Storyteller is a self-hosted platform for ebooks with synced narration. This is basically self-hosted WhisperSync, for anyone familiar with that Amazon product.
It's currently made up of two self-hostable backend systems and a mobile app for reading and listening to the books it produces. Technically it uses an open spec, EPUB 3's "Media Overlay", for syncing the narration, but very few ebook apps actually support Media Overlays, and even fewer work well and have nice interfaces.
The mobile app is available on the Apple App Store as "Storyteller Reader", and I plan to release it for Android as well early next year.
Anyway, I hope someone finds this interesting or useful!
Also, my experience was that audio and text versions are often very different (e.g. the audio having an intro missing from the text). It'd be very interesting to know how well Storyteller handles such cases. Does it require manual audio/text editing or handle the differences automatically?