If you use Calibre to manage your e-book collection, there’s a new update worth grabbing.
Version 9.10 (download here) isn’t a flashy release packed with headline features, but it does add several improvements that should make life easier for people who spend a lot of time inside the open source e-book manager.
The biggest addition is aimed at the Content Server. It now gets a modern interface with a sidebar that makes navigating libraries much less clunky than before. Better yet, if you’re running the server over HTTPS, it can now be installed as a Progressive Web App. That means your Calibre library can feel much more like a native application on phones, tablets, and desktops.
Book editors get a few welcome upgrades too.
Saved searches can now be filtered using keywords, which should save some frustration if you’ve accumulated a long list of them over the years. The image compression tool also gains the ability to convert PNG files to JPEG or WEBP, making it easier to shrink bloated e-books without manually processing images elsewhere first.
Under the hood, Calibre now supports CSS Level 4 selectors, improving compatibility with more modern EPUB styling techniques. The cover grid has also been tweaked so oversized images used as textures no longer spill awkwardly beyond the viewport.
If you’re someone who annotates heavily, you’ll appreciate another small improvement. The annotations browser can now filter by custom annotation styles, making it easier to track down specific notes or highlights in large libraries.
As expected, there are bug fixes too. Windows users should be happy to see a fix for IME input issues when typing notes for highlights. There is also a repair for a regression introduced in version 9.8 that prevented errors from AI plugin providers from being displayed to users.
Security wasn’t ignored either. Calibre 9.10 addresses CVE-2026-53511 by disabling Python templates when reading book metadata.
The release also updates several built-in news sources, including The Week, Economist Espresso, and Horizons.
Calibre isn’t the kind of project that tries to reinvent itself every six months. Instead, it keeps getting a little better with each release, and that consistency is a big reason why it remains the gold standard for managing e-books on Linux, Windows, and macOS.
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