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.

• Edit book: Allow drag and drop of images onto the image editor
• Edit book: Allow import of multiple files at once, via File->Import files into book
• Edit book: Show the name of the current character to the left of the cursor in the status bar. Can be turned off via Preferences.
• Edit book: Automatically replace HTML entities as they are typed. This can be turned off in the Preferences.
• ToC Editor: Allow bulk renaming of items. Simply select the items you want to rename, right click and choose bulk rename. Useful if, for instance, you want to rename all the items to be Chapter 1, Chapter 2 and so on.
• Edit book: Allow linking of stylesheets into HTML files automatically. Right click on the selected HTML files in the File browser and choose 'Link stylesheets' to have the tags for the sheets automatically inserted.
• Edit book: When deleting files, automatically remove all entries that refer to them from the ToC

• ToC Editor: When auto-generating the table of contents from headings or XPath, if an element is at the top of the file, link only to the file instead of to the element.
• Edit book: When splitting files, name the newly created file with a _split suffix.
• Edit book: Fix position syncing incorrect when in HTML files that contain tags with charset encoding declarations over more than a single line
• Edit book: Automatic correction of font family names not quoting family names with spaces in them if the original, incorrect family name did not have a space.
• Title casing: Fix presence of some non-English characters or smart punctuation causing all-caps text to not be properly titlecased
• Edit book: Fix a bug preventing marking an image as cover in a book that previously had no cover
• Edit book: Fix a typo causing the preferences for which windows occupy which corners to not work
• Edit book: Fix crash that happens sometimes when deleting multiple files.
• Edit book: Handle EPUB files which contain opf files with no tags
• Edit book: Fix deleting a file that is currently open in an editor, not auto-closing the editor
• DOCX Input: Fix error when converting DOCX file that contains only image based links and no text based links.