A native Kindle → Hardcover.app sync.

Website · Download · Changelog

Read on your jailbroken Kindle as usual. Endpaper is a small background program that sends your reading progress to Hardcover.

• Progress: the page you reached, after you close the book or the Kindle goes to sleep. Forward only: it never moves your progress back.
• New books: a book you start reading is added to Currently Reading.
• Finished books: marked Read at the end of the book.
• Re-reads: starting a finished book again starts a new read.
• Star ratings from the Kindle's end-of-book screen.
• Highlights and notes: sent as private journal entries.

Endpaper is an independent project, not made by or affiliated with Hardcover or Amazon.

It only reads the Kindle's files. It does not change the Kindle reader or your books, and it works with the stock Amazon reader (no KOReader).

Requirements

• A jailbroken Kindle that can run scriptlets (.sh files that show up in the library). Current jailbreaks can do this.
• A Hardcover account.
• Wi-Fi for syncing. Without Wi-Fi, changes wait and are sent later.

Tested on one Kindle with firmware 5.17.1. Other models and firmware should work but are not tested yet; please report results.

Install

Before you start (recommended): unlink Goodreads on the Kindle (Settings > Your Account; the exact menu name varies by firmware). Endpaper works either way, but with Goodreads linked the Kindle shows a Goodreads "Rating Error" box after a star rating on sideloaded books, and it may also send your progress to Goodreads. Your star taps still reach Hardcover when Goodreads is unlinked.

1. Download endpaper-<version>.zip from the releases page.
2. Connect the Kindle to your computer with USB.
3. Unzip the file onto the Kindle drive. You get:
   • documents/Endpaper.sh: the Endpaper item in your library
   • endpaper/: the program
4. Eject the Kindle.
5. In the library, tap Endpaper. Tap Sign in, scan the code with your phone (or open the link and enter the code), and approve.

Sync now runs in the background. You do not need to open Endpaper again.

After a restart of the Kindle, tap Endpaper once to start sync again.

Use

Tap Endpaper in the library to see the status and these options:

Button	What it does
Sync now	Checks your books at once (normally automatic)
Import old highlights	Sends highlights and notes made before you installed
Check setup	Tests each part and shows OK / FAIL
Save log for support	Writes endpaper/endpaper-log.txt to the USB drive
Sign out	Removes your sign-in from this Kindle
Stop sync	Stops until you tap Endpaper again
Uninstall	Removes everything (see below)

Leave the page with the Home button.

Tips

• A book that is not found on Hardcover is skipped. Add the right edition to any shelf on hardcover.app; it syncs within an hour.

Update

When a new version is out, the Endpaper page shows an Update available banner.

1. Download the new zip from the releases page.
2. Connect USB and unzip it onto the Kindle drive (replace the old files, or delete them first: either is fine).
3. Eject and tap Endpaper. The new version starts; you stay signed in.

Uninstall

Tap Endpaper > Uninstall. It removes the app, its settings and your sign-in from the Kindle.

Endpaper never deletes anything on its own. If you only delete documents/Endpaper.sh and the endpaper folder over USB, sync stops at the next restart, but your sign-in and settings stay in /var/local/endpaper (a few KB). To remove them too, install again and use Uninstall.

Privacy

Your Hardcover sign-in stays on the Kindle (/var/local/endpaper). The program talks to Hardcover, and, while the Endpaper page is open, at most once an hour to GitHub to look for a new version. Highlights and notes are sent as private entries. Nothing else is collected.

Troubleshooting

1. Tap Endpaper > Check setup.
2. Tap Save log for support, connect USB and send endpaper/endpaper-log.txt with your report.

For developers

go test ./...
HC_CLIENT_ID=<your Hardcover OAuth client id> ./scripts/build.sh   # dist/endpaper-<version>.zip

One static ARM binary in Go (no system libraries needed). How it works: docs/architecture.md; all docs: docs/.

cmd/endpaper/        the program: launcher, daemon, local page API
cmd/endpaper/ui/     the Kindle page (embedded in the binary)
internal/            readers, sync logic, Hardcover client, state DB, ...
packaging/kindle/    library item (Endpaper.sh) and its cover
scripts/build.sh     builds dist/endpaper-<version>.zip
site/                the website (GitHub Pages)
docs/                architecture, testing, decisions, research

Releases: set the repository secret HC_CLIENT_ID, then push a tag such as v0.1.0. The release workflow tests, builds and publishes the zip.

License

MIT, see LICENSE.