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.

• Add an option to control how completion works when editing authors/tags/series/etc.
• Edit book: Add a check for too large HTML files when running the check book tool.
• Conversion: Sort the CSS rules in the output stylesheet using a 'natural' sort algorithm, so that calibre2 sorts before calibre10.
• Cybook Orizon driver: Upload cover thumbnails in the correct format and add an option to control what directory books are sent to on the SD card
• Portable installer: Do not ask the user for confirmation when upgrading an existing installation during an automated install
• Linux/OS X driver for Trekstor Pyrus LED
• Driver for Tagus Lux

• MOBI Output: When text indent is specified as a percentage in the input document, prevent the generated MOBI from having too large an indent if the user chooses a large output profile like tablet.
• Edit book: Fix live replacement of entities not working on some non-US keyboard layouts.
• Fix titlecasing of words not capitalizing the first letter, if the first letter is not an English character.
• Edit book: Ensure that multiple edit book windows are grouped in a separate group from viewer windows in the Windows 7 taskbar. Also change the icon color to blue to more easily distinguish it from the viewer icon
• Edit book: Fix a bug in the regex engine that calibre uses that could cause various incorrect results in some special circumstances.
• Edit book: Replace buggy Qt supplied actions in the context menu for the editor widget with properly implemented ones
• Book list: Fix sorting on fields that are not viewable as columns not being restored on calibre restart. Also fix sorting on the Title field via the right click menu not being restored.
• Windows 64bit build: Fix corrupted images in MOBI files causing crash.
• Edit book: Prettify html in newly created books.
• AZW3 Input: Handle azw3 files that contain some empty individual HTML files
• Comic Input: Fix a regression to comic input in 1.15 that could cause some comics to be rendered as black or white pages.