An extremely capable ebook management program by Kovid Goyal.
Calibre (previously Libprs500) is an ebook management program, conversion tool, and includes an eBook Reader. It is free, open source and cross-platform in design and works on Linux, MacOS X and Windows. Calibre is meant to be a complete e-library solution and thus includes library management, format conversion, news feeds to eBook conversion as well as device sync features. It can convert from HTML, LIT, RTF, TXT, MOBI, and PDF (simple text+few images), and ePUB. Multiple HTML or HTML with images will work if they are zipped up together. It can also automatically download and convert RSS feeds. It can output LRF, ePUB, and/or MOBI.
Calibre can be used as a viewer for all the major eBook formats. Calibre only works with non-DRM versions of all the eBook formats.
 Conversion tool
Conversion from PDF can be problematic as it is for most other tools. Simple text with a few images will work fine but a complicated PDF or one that has been edited several times can be a problem. PDF files can sometimes consist of images that look like text. These will remain as images in the converted file. PDF can also represent some two character sets as ligatures using embedded fonts to display. These could be dropped during conversion.
It has been reported that ePub to FB2 conversion loses internal links.
 Library Management
Calibre is primarily a eBook cataloging program. It manages your eBook collection for you. It is designed around the concept of the logical book, i.e. a single entry in the database that may correspond to eBooks in several formats.
Calibre support sorting the books in its database by:
- Size (Max size of all formats)
It also supports extra metadata fields that can be searched on:
- Comments: A general purpose field that can be used to describe the book, add notes on it, etc.
- Tags: A flexible system to categorize books. You can tag any book with any custom tag to indicate subject, read status, category, etc.
The database view also supports filtering by searching on the metadata. You can perform advanced searching on individual metadata fields by clicking the advanced search button to the left of the search bar.
You can export subsets of the books in your collection by using the Save to disk button.
You can fetch metadata from the Internet for a book based on its ISBN number or its title/author, instead of manually entering the metadata. You can also fetch a cover image based on the ISBN number.
 Sharing and publication with Dropbox
With Dropbox, the syncing and publishing tool (free for 2Gb), it's easy to setup Calibre so that your eBook collection is always available on the internet, and synced across multiple computers. This is explained here on the calibre2opds FAQ.
The free and opensource calibre2opds can be easily used to generate standard OPDS catalogs that can be read by compatible eBook readers (such as Aldiko, Stanza, QuickReader, and MegaReader). Combined with the Dropbox sharing instructions above, this makes your entire Calibre library accessible on your smart phone, or even a netbook or tablet computer running Firefox and EPUBReader.
 ePub Editor
 Usage of regular expressions inside Calibre
Calibre supports the use of regular expressions in multiple places including its editor. An introduction to regular expressions and their usage inside Calibre is available here.
 Get Calibre
- Windows installer
- Mac Installer
- Linux installation instructions or just: sudo python -c "import urllib2; exec urllib2.urlopen('http://status.calibre-ebook.com/linux_installer').read(); main()"
Calibre accepts plugins that can change its behavior and extend its ability to support more features. Check Custom GUI plugins in our forum for more details.