Calibre 9.18 brings enhanced accessibility, KOReader sync, and support for OPDS 2.0 feeds

The popular open-source e-book management software Calibre has released version 9.18, headlined by a major new suite of accessibility tools. The “Edit Book” editor now includes a dedicated accessibility tool that lets authors set the languages of a book and its individual HTML files, edit alternative text for every image, including inline SVGs, from a single place, and manage EPUB accessibility metadata. Complementing this, the automated “Check book” feature now flags a range of accessibility problems, such as images lacking alt text, HTML files without a declared language, headings that skip levels, and missing accessibility metadata, many of which can be repaired automatically.

Beyond accessibility, the release brings notable improvements to Calibre's built-in content server, which now acts as a progress synchronization server for the KOReader e-reader app, letting readers pick up where they left off across different devices and even different formats of the same book. The server also gains support for OPDS 2.0 feeds, streaming of CBZ comic archives with proper manga reading-direction support, and full-text searching of book contents. Additional enhancements for keyboard and screen-reader users round out the server's accessibility push.

In addition, the update offers quality-of-life refinements throughout the ecosystem: the e-book viewer can now restrict searches to the current chapter, the command-line calibredb tool gains commands for managing notes, annotations, virtual libraries and the trash bin, and date searching expands with relative terms like “lastmonth” and “yearsago”. New catalog additions include the Standard Ebooks, DOAB and DOAJ stores for the “Get books” feature, alongside the ability to verify exported Calibre backups without restoring them. The release is available for download from the official Calibre website.