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 editing an unzipped EPUB (a folder) as a book
• Useful if you wish to store your ebook in a version control system and edit it directly with the calibre ebook editor (File->Open folder as book)
• Edit Book: Allow easily removing items from the popup menu for the 'Insert tag' button
• Make Tag Browser more useable with keyboard shortcuts. Configure the keyboard shortcuts in Preferences->Keyboard->Tag Browser
• ToC editor: Add context menu item to change selected entries to upper case

• Edit Book: Preview panel: Render in XHTML mode. Fixes svg elements using a global svg namespace not rendering.
• Tag Browser: Fix clicking on first-letter groups for series not working
• DOCX Output: Ignore corrupted images in the input instead of erroring out on them.
• E-book viewer: Fix keyboard shortcut to toggle table of contents not working when ToC window is made floating.
• Allow ebook-metadata to work with read-only files when no options are specified to change metadata.
• Tag mapper: When the replacement tag contains commas, create multiple tags instead of replacing the comma with a semi-colon.
• HTMLZ Output: Set the HTML