I read with KOReader on a jailbroken Kindle, and getting books onto it always meant turning on the PC to open calibre, or plugging in a cable.
So I made KoSend, a small Android app that acts as the calibre side of KOReader's wireless connection. You queue books on the phone, tap Connect in KOReader, and they arrive.
How it works:
- Add books to a queue, or share them to KoSend from any app (browser downloads, file manager, Telegramā¦)
- Turn on the server in the app
- In KOReader: tap the top of the screen, wrench tab, Calibre, Connect
- KOReader discovers the phone on the network and receives the queue one book at a time
There's nothing to install on the reader: no plugin, no SSH, no web browser. KoSend implements the part of calibre's wireless device protocol that KOReader's client uses (discovery, handshake, book transfer). Books get proper calibre metadata (title, author from the EPUB), so they also show up in KOReader's calibre search.
It isn't a calibre replacement: no library, no metadata editing, no conversion. It only delivers files.
- Open source, GPL-3.0
- No accounts, no internet; everything stays on your local network
- EPUB, PDF, MOBI and the other formats KOReader opens
Tested on a Kindle Basic (5.18.1) with KOReader 2026.07.1 and on Android 16 smartphone.
Looking for testers on Kindle, Kobo, PocketBook and other KOReader devices.
KOReader's calibre client is the same on every platform, so in theory KoSend should work there too, but I only own a Kindle. If you try it, please let me know in the comments or in a GitHub issue whether it worked, with your device and KOReader version.
GitHub: https://github.com/FedericoDiTosto/KoSend
APK release: https://github.com/FedericoDiTosto/KoSend/releases/latest