Last week's update improves upon the ebook editor which was added in December; users can now not only edit and save an ebook in in Epub and Kindle formats, they can also compare two ebooks and see the differences. An earlier update also added a spell checker for thse uv os woh ned it.
Calibre is the leading free ebook library management app, as well as the most widely used. At last count it had been installed almost 25 million times, and is in active use on over 3.5 million computers. The app supports conversion to and from a wide variety of ebook formats, and it also helps users to manage their ebook collection both on their PC as well as on almost any reading device they own, be it ereader, tablet, smartphone, or what have you.
Initially launched in October 2006, calibre was originally intended to support the then new Sony Reader PRS-500. A certain grad student wanted to use his new ebook reader with Linux, so he reverse engineered the USB driver for Sony's proprietary software. From those humble beginnings came libprs500, which quickly added features and support for more devices and ebook formats, growing into the best open source ebook management tool anywhere. After it was clear the focus had expanded beyond Sony’s first ereader, libprs500 was renamed as calibre in mid-2008.