What is calibre used for?

calibre is a cross-platform e-book manager that views, converts, edits and catalogs e-books and syncs with e-reader devices. It is a good fit for managing a personal e-book library and converting books between formats for a Kindle.

Is calibre open source?

Yes. calibre is open source under the GPL-3.0 licence. Its source code is on GitHub at kovidgoyal/calibre and is written mainly in Python.

Yes. calibre is open source, so the software itself is free to use.

Can I self-host calibre?

Yes. calibre can be self-hosted on your own server or infrastructure; there is no official hosted version.

What is calibre an alternative to?

calibre is an open-source alternative to Kobo. Other open-source alternatives to Kobo include Calibre-Web, Grimmory and KOReader.

Is calibre actively maintained?

Yes. The most recent commit to calibre was on 2 October 2026, and the latest release is v9.15.0, published on 18 September 2026. The project has 26k stars on GitHub.

calibre: open-source alternative to Kobo

About calibre

calibre is an e-book manager that can view, convert, edit and catalog books across every major e-book format. It can communicate with e-reader devices, fetch metadata for your books from the internet, and download newspapers and convert them into e-books for reading. It runs on Linux, Windows and macOS, is written in Python, and is released under the GPL-3.0 license. The repository is the official source.

The project points to a user manual for usage, a screenshots page, and build instructions for creating binaries and installers for every supported platform. Bug reports and feature requests go to a tracker on Launchpad, while GitHub is used only for hosting code and pull requests. calibre is built by volunteers from around the world, and the project asks users who find it helpful to donate to support development. Source tarballs of each release are available.

Key features

View, convert, edit and catalog e-books
Supports all major e-book formats
Transfers books to e-reader devices
Fetches book metadata from the internet
Downloads news and converts it to e-books
Runs on Linux, Windows and macOS

Good fit for

→Managing a personal e-book library
→Converting books between formats for a Kindle

Built with: Python
Tags: ebook-manager; ebooks; epub; kindle; library; python; converter; cross-platform

calibre: questions and answers

What is calibre used for?: calibre is a cross-platform e-book manager that views, converts, edits and catalogs e-books and syncs with e-reader devices. It is a good fit for managing a personal e-book library and converting books between formats for a Kindle.
Is calibre open source?: Yes. calibre is open source under the GPL-3.0 licence. Its source code is on GitHub at kovidgoyal/calibre and is written mainly in Python.
Is calibre free?: Yes. calibre is open source, so the software itself is free to use.
Can I self-host calibre?: Yes. calibre can be self-hosted on your own server or infrastructure; there is no official hosted version.
What is calibre an alternative to?: calibre is an open-source alternative to Kobo. Other open-source alternatives to Kobo include Calibre-Web, Grimmory and KOReader.
Is calibre actively maintained?: Yes. The most recent commit to calibre was on 2 October 2026, and the latest release is v9.15.0, published on 18 September 2026. The project has 26k stars on GitHub.