New in calibre 4.0

Welcome back, calibre users. It has been two years since calibre 3.0. This time has been spent mostly in making the calibre Content server ever more capable as well as migrating calibre itself from Qt WebKit to Qt WebEngine, because the former is no longer maintained.

The Content server has gained the ability to Edit metadata, Add/remove books and even Convert books to and from all the formats calibre itself supports. It is now a full fledged interface to your calibre libraries.

The change to use Qt WebEngine has entailed a complete rewrite of various parts of calibre, including the E-book viewer, PDF Output, Book details etc. Every attempt has been made to preserve features and functionality in a backwards compatible way, see below for a list of some known incompatibilities.

The new Content server capabilities The server has gained all the major capabilities of the main calibre interface. You can now edit metadata, convert books, and add/remove books and formats just as is possible with calibre itself. To see a brief tutorial describing how to access these features via the server interface, click here.

All new e-book viewer The calibre builtin E-book viewer has been completely rewritten. The new design emphasizes the book text, with no visible controls. The viewer now also shares a codebase with the in-browser viewer which will make developing new features such as the upcoming support for annotations much easier.

Backwards incompatibilities There are a few minor backwards incompatibilities to be aware of in calibre 4, because of the replacement of Qt WebKit with Qt WebEngine . The Book details panel now no longer uses a full browser engine for rendering. This makes it faster and less resource intensive, however it supports less HTML and CSS, which means if you used advanced styling in your comments it may not fully work. See here for the supported HTML subset. The markup needed for header and footer templates when converting to PDF has changed. See the manual for details.



This is an appropriate time to throw out a big thank you to the calibre community who have contributed selflessly of their energy and enthusiasm — without which many of the features above would never have seen the light of day.

Note that some of these features were actually introduced during the lifetime of the 3.x series. This document describes new features as compared to 3.0

See what was new in previous major calibre releases: 3.0, 2.0, 1.0, 0.9, 0.8, 0.7.