Calibre is a free and open-source e-book management software that allows users to manage their e-books, convert between different e-book formats, and sync e-books with various devices. It was first released in 2006 and has since become one of the most popular e-book management tools available.

One of the most notable features of Calibre is its ability to organize e-books into different categories and add tags, making it easy to search and locate specific books. It also allows users to edit the metadata of their e-books, including the title, author, and cover image, and can even download missing metadata from online sources.

Calibre also provides a powerful e-book conversion tool, allowing users to convert e-books from one format to another, such as from EPUB to MOBI, or from PDF to EPUB. This is particularly useful for those who want to read e-books on different devices that may not support the same file format.

In addition, Calibre supports a wide range of e-book readers, including Amazon Kindle, Barnes & Noble Nook, and Kobo e-readers, and can automatically sync e-books with these devices. It can also connect to online e-book stores, such as Amazon and Google Books, allowing users to browse and purchase e-books directly from within the software.

Calibre is an essential tool for anyone who reads and manages e-books. Its powerful features and easy-to-use interface make it a must-have for anyone looking to organize, convert, and sync their e-book library.

Key Features:

• Library management system to organize e-book collection
• Format conversion for compatibility with different devices
• Built-in editor to modify e-book metadata and table of contents
• E-book viewer with customization options
• Integrated web browser for downloading e-books
• Synchronization options for keeping e-book collection up-to-date across devices
• Extensible with plugins to add additional features and functionality.

• E-book viewer: Make the list of bookmarks a dockable window that can be kept open while reading the book
• E-book viewer: Make the Table of Contents panel a dockable window so it can be moved around and even made into a separate floating window
• E-book viewer: Allow reloading the current book by pressing F5 or Ctrl+R
• Edit Book: Allow changing the case of selected text by right clicking and choosing the appropriate change case action.
• Driver for Kiano Booky Light.
• calibredb list: Have --for-machine dump the output in JSON instead of using ASCII separators, as most scripting languages have JSON parsers builtin
• zsh completion: Complete filenames inside epub files for ebook-edit
• ebook-edit: Allow specifying multiple internal files to open and get rid of the no longer needed --edit-file option

• Fix over-aggressive caching causing multiple cover grid emblem rules to not work.
• Edit Book: Fix position syncing and Live CSS not working if the opening tag is split over multiple lines
• EPUB metadata: When updating the language in an EPUB file, preserve the country code, if the new language is the same as the original language in the EPUB file.
• Edit Book: Fix choosing default dictionary based on language tag in the OPF ignoring the country code
• Edit Book: Fix a regression that caused clicking on links in the preview panel that lead to destinations in the same HTML file popping up a spurious error message.
• Fix regression that caused tags to not be sorted when displayed in the book details panel.
• Edit Book: More robust implementation of current tag detection for Live CSS. Now uses the same logic as matching tag highlighting.
• Edit Book: When highlighting the tag the cursor is currently inside, if the cursor is inside the definition of an opening tag, highlight that tag rather than its parent.
• Edit Book: Check Book: Do not run the rest of the checks if parsing errors are found, to prevent the checkers from raising unhandled errors