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: Add support for third party plugins to extend the editors functionality.
• calibredb list: Add a --for-machine option that causes the output to be made in a form more easily parsed programmatically (it uses ASCII field and record separators)
• Book details panel: Automatically convert ISSN identifiers into links to the periodicals page on worldcat.org
• Edit Book: When re-arranging the toolbars inside an individual file editor, save the new toolbar layout so that it is re-used in the future. Also apply the changed layout to all open editors of the same type.
• Edit Book: Make the undo/redo/cut/copy/paste buttons on the editor toolbar also configurable, so they can be removed via Preferences->Toolbars, if needed.
• Edit Book: Allow editing xpgt (Adobe Page Template) files as XML.
• Edit Book: Allow the action to launch the saved searches dialog to be added to the global toolbars
• Book details panel: Add an option to make clicking on the author name search the calibre library for the author instead of opening the wikipedia page for the author. To use it got to Preferences->Look & Feel->Book Details.

• Fix published date not being merged when merging book records
• Embed metadata tool: Fix error when trying to embed metadata in corrupted MOBI files or files of other types that are marked as MOBI in the library
• Edit Book: Make the warning dialog that pops up when you try to quit while the editor is saving changes in the background a little more clear.
• When generating covers, do not render soft-hyphens in the text as hyphens.
• Conversion: Fix a bug processing the CSS font shorthand property when the line-height is specified in em or percentage units
• calibre-customize: When building plugins from a directory, exclude known version control subdirectories