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.

• Cover Browser: Add an option to show covers with their original aspect ratio instead of resizing them all to have the same width and height. Option is in Preferences->Look & Feel->Cover Browser.
• PDF Output: Enable using javascript inside header and footer templates
• Edit Book: When generating an inline ToC add a class attribute to all
  tags to make it easy to style a particular level of the ToC
  • Use abstract named sockets on linux for IPC, to avoid use of temp files for sockets
  • Drivers for the N800 and N950 Nokia MeeGo tablets
  • Edit Book Saved searches: Allow saving normal mode searches as well
  • Edit Book Saved searches: Add import/export functionality
  • calibredb add: Add option to specify language when adding books
  Bug Fixes
  
  • AZW3 Input: Handle files with garbage bytes in their table of contents.
  • DOCX Input: Fix text from some paragraphs not being converted if the paragraph contains an inline forced page break and no formatted text or line breaks.
  • calibre-customize: Do not error out if one of the installed plugins has no customization help when listing all plugins
  • Edit book: Fix error when exporting files on some windows systems with non UTF-8 filename encodings
  • Edit Book: When beautifying treat tags as block tags
  • Linux binary build: Fix worker processes not working on linux systems with bash >= 4.3
  • PDF Output: Fix using __SECTION__ in header and footer templates resolving to the inscorrect section if a page with no sections follows a page with multiple sections.
  • Cover Browser: Fix visual 'pop' when scrolling the first time
  • Grid View: Allow the left and right arrow keys to traverse over rows.