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0.3.0

Books open at once, and the reader gets the new look, with a header and footer like Apple Books. Released October 3, 2026, on calibre 9.15.

Opening a book used to take about two seconds. Almost all of that was the reader starting up, not the book. Now a reader is ready and waiting, so a book shows in about a tenth of a second.

  • It works the same way. Double-click a book, press Read, or use the toolbar. Nothing to learn.
  • The first open of a book takes a moment longer, while the book is unpacked. After that it is quick every time.
  • A new reader gets ready about half a minute after you open a book, so it never slows the one you are reading.
  • The waiting reader uses about 280 MB of memory while the main window is open. Turn it off with Ready reader under the Calibre Zen button on the toolbar.
  • Two books opened within half a minute. The second one opens the usual way, in about two seconds.
  • The “single window” reader option sends every book to the reader that is already open, so the waiting reader is not used then.

The reader was the last window still in calibre’s old look. Now it matches the rest of the app, in light and dark.

The header, the footer, and Themes & Settings.

Click in the middle of the page, right-click, or press Esc. A bar appears at the top and the bottom, and the page stays in view. Click the page again to hide them.

  • The header shows the book’s title and the chapter you are in. Its buttons open the contents, search, bookmarks and highlights.
  • Themes & Settings makes the text smaller or larger, and shows every reading theme in its own colours. Click one to switch.
  • The footer has a button for the previous and next page, and for the previous and next chapter. The bar between them shows how far you are. Drag it to jump anywhere in the book.
  • More, the three dots, has every other action, like Go to, Read aloud and Print.
More, in dark mode.
The book at the top, and the chapter you are reading marked.
  • The book you are reading sits at the top, with its cover, title and author. The info button opens the book’s details.
  • One chapter is marked, the one you are reading. Before, every heading on the screen was marked at once.
  • The panels for search, highlights and bookmarks have the same tidy rows.
The reader's Preferences.
  • Preferences, Go to and the book’s details are clean lists and forms.
  • Line icons replace the old filled ones, the same as in the main window.
  • Select some text and a floating bar appears, with round colour swatches for highlights.
  • Picking a theme closes the bars, because the book is drawn again in the new colours.
  • The Highlights button shows a picture icon. calibre uses the same icon for viewing an image, so it stays for now.
  • Books that read right to left keep the footer’s arrows pointing the usual way, for now.
  • calibre’s own reader look is one click away. Turn off Reader look under the Calibre Zen button on the toolbar.

Download calibre-zen

The list of downloads could not be loaded just now. Every release, with a file for Windows, macOS and Linux, is on GitHub.