Cobalt is an open-source application platform for Kobo e-readers: a launcher, a signed App Store, a Rust SDK, and a runtime that keeps every app in its own unprivileged process.
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Read books and papers, follow feeds, play a game, listen to audio, or check a task without changing devices. Install only the apps you want, then update or remove them over Wi-Fi.
These are the Kobos somebody has physically tested. Cobalt runs on others too: it shows what has not been tested about your device and asks once before it starts. To get yours onto this list, join an existing device thread or create a new one.
Cobalt adds a place for useful e-ink apps while keeping the reading experience and library already on the device.
Open Cobalt from the reader's menu, use an app, then return to the original reader. A restart always returns there too.
After one USB setup, browse, install, update, and remove apps over Wi-Fi. You do not need to reconnect a cable for every app.
Apps are separate choices, not a bundle you must accept. Remove one without disturbing the others or reinstalling Cobalt.
Large touch targets, deliberate refreshes, readable type, and simple screens make the device feel like itself rather than a small tablet.
Read complete papers with sections, mathematics, tables, and figures. When work needs a simple decision, answer it from the same screen.
You can install new apps from the Cobalt App Store over Wi-Fi.
Store-only by design: installing it proves delivery of an app the USB package never contained.
Review a small offline card queue with large reveal and answer controls made for an e-ink panel.
Browse Zotero collections, read metadata and indexed paper text, and keep papers available offline.
Browse available apps on the reader, install one over Wi-Fi, and remove it when you no longer want it. App updates arrive without reinstalling Cobalt.
Every package is checked before it opens. An interrupted install or update leaves the working version in place.
Cobalt updates remain separate from app updates, so the Store cannot replace the platform itself.
Start a Rust app, run it in the Cobalt simulator, test it on a supported reader, and submit it to Store. An app can ship without waiting for a Cobalt platform release.
Or from a terminal, which does the same thing:
curl -fsSL https://bandarlabs.github.io/Cobalt/install.sh | shThe complete walkthrough, including recovery steps, is in docs/INSTALL.md.
Safety
Cobalt does not replace Kobo's boot chain. Normal panel-write entry points require an exact hardware and firmware match, and a reboot returns to the stock reader. The first installation does modify files on the user storage partition, and it is provided without warranty.
The Clara BW, Clara Colour, Elipsa 2E, Clara HD, Libra 2, Libra Colour and Libra H2O are tested at the firmware and kernel versions in the device support matrix. Cobalt starts on other devices and firmware as well, after showing what has not been tested and asking whether to continue. Untested hardware is not verified hardware, and nothing here is a claim about it. Cobalt is an independent project, not affiliated with Rakuten Kobo.