Varbook — Your books, everywhere
varbook.hophop.be
Self-hosted EPUB library with cross-device reading sync. Read on your e-reader, pick up where you left off in the browser.

I read every single day. At home it’s on my Kobo running KOReader (yes, I’m that open-source guy), and I love it. The problem: I don’t always have the e-reader on me. On the train, at work, waiting somewhere — I just have my phone.

I tried Kobo’s own Android app to bridge the gap and… I really didn’t like it. Promos everywhere, adding your own books is a pain, the reader itself feels clunky, and the Wi-Fi handling is annoying.

So I built my own thing: Varbook, a small self-hosted EPUB library.

Varbook library on mobile: dark UI with a "Continue Reading" section showing progress bars and reading time, search bar, status/sort filters, and a book cover grid below

You drop EPUBs into it in one click. From there:

  • They’re readable on your phone through a simple but well-made PWA. Books are cached locally, so you can read offline; when you’re back online your reading position syncs to the server.
  • The server exposes everything over OPDS, so any compatible app works (KOReader, Moon+ Reader, etc.).
  • I also wrote a KOReader plugin that pushes/pulls your reading position to the server in a single gesture.

Varbook EPUB reader on mobile: dark theme, large serif font, chapter title and progress bar at the bottom showing 52.4%, reading time, and page count

My actual daily workflow:

  • Evening, at home: I wake up my Kobo in KOReader, tap the top-right corner → Wi-Fi turns on, my current book jumps to the right position, Wi-Fi turns back off to save battery.
  • I read.
  • Done reading: tap the top-right corner again → Wi-Fi on, my reading time + position sync to the server.
  • Next day, at work: I open the PWA on my phone. It drops me exactly where I left off, and syncs my position on every page turn.
  • Evening: back to the Kobo, which picks up my position from the phone.

All of this with fully open-source software, no commercial service in the loop, my books staying on my own server.

The trickiest part was cross-device position sync — every reader engine (epub.js in the browser, KOReader’s CREngine, Moon+) tracks position differently. Varbook uses a “pivot” format based on EPUB spine items (chapter index + percentage) so your position survives the jump from one device to another without throwing you 30 pages off.

Varbook reading statistics on mobile: KPI cards (17 books, 3 finished, 80h59m reading time, 2017 sessions), book status breakdown, and reading time by device (KOReader 8.8h, Moon+ 0.6h, Web Reader 71.6h)

It’s open source (MIT), built with Laravel + React, and ships as a single Docker container (SQLite by default, no external DB needed). The entire UI is translated in English, French, and Spanish.

Honest disclaimer: a good chunk of this is vibe-coded. That said, I’ve been a developer for 20 years, so it’s opinionated vibe-coding — I know what I’m looking at. It’s been used daily and intensively by about 5 people for the last 3 months, and I keep improving it regularly. It’s not bug-free, but I’d call it reasonably stable. I’m being upfront so you know what you’re getting into.

There’s a free public instance if you just want to try it without installing anything: https://varbook.hophop.be/

Happy to answer questions or hear what’s missing — it scratches my own itch, but I’d love to know if it’s useful to anyone else.

  • MagnificentSteiner@lemmy.zipEnglish
    46·
    1 hour ago

    There are already many self hosted services that can do this without vibe coding.

    Also, KOReader already syncs reading progress over OPDS without a plugin.

    • n2024@lemmy.worldOPEnglish
      9·
      12 hours ago

      Genuine question, which ones? I searched a lot before building this and didn’t find one that syncs both the reading position AND the reading time between a web reader and an e-reader. If you know one, I really want to hear it.

      Small correction: OPDS is just for browsing/downloading books, it doesn’t carry your reading position. KOReader syncs that through kosync, which is a different thing. And kosync only syncs the position, not the reading time. On top of that, the position is stored in a KOReader-only format (XPointer), while web readers use a different one (CFI), so they don’t understand each other.

      That’s the whole reason I made the plugin + my own “pivot” format: so my Kobo and my phone actually land on the same spot, with the reading time too. Maybe not the only solution, but I couldn’t find it ready-made.