Converting and exporting¶

EPUB is Bookx's native format. Other formats are converted to EPUB when you add them, and EPUB books can be converted to other formats on the way out.

Input formats¶

Output formats (Convert To)¶

Right-click a book → Convert To and pick a format.

Plug-ins can add more entries, shown as "name (.ext, plugin)". See Plugins and patches. Right-click also offers Save a Copy and Show in Files.

When you send a book to a device, Bookx converts it to the device's format automatically. A book that holds several formats sends the one that suits the device (KEPUB to a Kobo, AZW3 or MOBI to a Kindle, EPUB to the rest) without converting; conversion starts from the EPUB.

Bookx does not convert files with copy protection (see Copy protection). If a conversion fails it tries the next format the device opens. See Devices and sharing.

How well each format converts¶

Bookx's converters are compared with Calibre's on a set of test books (EPUB 2/3, FictionBook, Word, ODT, RTF, Markdown, HTML, text in several encodings, comics and files made by Calibre) for every pair of formats. A format "keeps" a feature when a book converted into it and read back still has it.

Parity with Calibre: for the test books no format pair loses more than Calibre does. Known small differences: text output starts with the title and author; Bookx does not invent a cover, a title page or a contents page for books that have none; Calibre's own PML, RTF and text files glue list items and table cells into one word, which no reader can undo. Details for contributors are in docs/convert-parity.md.

Check before sending or converting¶

Right-click one or more books → Check Before Sending. Bookx runs the EPUB validator and the rules of the place the book is going to (choose Any device, Kindle, Kobo or E-mail at the top) and lists, per book, the blocking problems (the device or converter will refuse or break the book: a broken mimetype, no language for Amazon, DRM, a file over 25 MB for e-mail) and warnings (no cover, no author, validator warnings). Problems that can be repaired automatically are marked can be fixed; Fix All repairs them and keeps the original of each book in the library's .bookx/preflight-backups folder.

Switch on Check automatically before converting or e-mailing in the same window to make this a step of Convert To and Send by E-mail: the window only appears when something was found, and Continue Anyway goes on. Sending to a device in the Device window does not run this check yet.

Conversion report¶

After Convert To, a small text file <output>.report.txt is saved next to the converted file. It names the target, the size before and after, what the checker found in the source book and (for EPUB and KEPUB results) in the result, and says when embedded fonts or SVG images may not be kept in the chosen format. Switch it off with Save a report next to converted files in the Check Before Sending window. On the command line, bookx-cli convert in.epub out.txt --report also lists what the output format cannot hold (pictures, cover, contents, links, series) and what the conversion steps changed; --report FILE saves it (a .json name gives JSON).

Command line¶

bookx-cli convert picks the output format from the output extension:

bookx-cli formats
bookx-cli convert book.fb2 book.kepub.epub --smarten --device kobo
bookx-cli convert book.epub book.mobi --preset "Kindle (MOBI)"
bookx-cli presets

Options include --smarten/--unsmarten, --unwrap-lines, --remove-unused-css, --remove-blank-paragraphs, --remove-fake-margins, --auto-toc, --split-large-html, --epub-version 2|3, and metadata overrides such as --title, --author, --series and --cover. See Command line.

Exporting annotations¶

Right-click → Export Annotations writes your highlights, notes and bookmarks as Markdown, HTML, JSON, plain text, an Obsidian note, Kindle clippings or Readwise data; Main menu → Export All Annotations does it for the whole library. Import Highlights brings in the ones from a Kindle, KOReader, a Kobo or calibre. See Highlights and notes.