Calibre is a free open-source eBook management system. It was originally developed in 2006 as a way of allowing Linux users to read files from the Sony PRS-500 reading device. Since then the main developer, Kovid Goyal, and his team have continued to add improvements and extra capabilities at an amazing rate, putting out new releases every fortnight or so, and Calibre has developed into an extremely powerful tool for maintaining eBook collections in a wide range of formats. Calibre is not (yet) included in the standard Mint distros, but can be installed with the Synaptic Package Manager.
Calibre works by ‘importing’ eBook files into a data folder. This is divided up into subfolders by authors’ names, with subfolders for each title. In addition to the eBook file itself, Calibre creates one or more metadata files, which record ‘metadata’ such as when the book was added, whether it’s been read, and so on. Calibre also links up to websites which store cover pictures and other information about books, so these can often be downloaded and added to books that don’t have them.
The main Calibre screen shows a table of information, with each book represented by one row. The information in the table can be customised, but the default layout includes Author, Title, Date Modified – i.e. when the book was imported – Rating, Publisher, Publication Date and Size (in megabytes). You can add other columns such as Formats, and define your own data fields – e.g. ‘Pseudonym’. The table can be sorted by clicking on the column headings, and filtered by typing a search term in the filter box at the top.
Double-clicking on a book brings it up in Calibre’s own E-Book Viewer, a fairly simple page viewing application which allows you to add bookmarks or look up words in a dictionary. You can adjust the text font and size, copy text and print the pages. Your progress through the book is tracked by a scroll bar, and an optional numerical display at the top left. When you leave a book, the viewer will reopen it at that page when you return. A Preferences button in the left toolbar controls an impressive number of display options.
A panel at the left of the main Calibre screen allows you to filter your books by Author, Format, Series or Publisher. You can also use the Ratings you have given (a five-star system) or the Tags. Tags can be simple keywords you’ve added yourself, or more elaborate descriptions – similar to the ‘blurbs’ found in printed books – that can be downloaded from the Web. One of the main sources of tags is the Amazon website.
The items in the default Calibre toolbar give a good indication of its capacity. Most of these have several options and a range of settings:
- Add Books – used for importing books to Calibre from directories or memory devices. Duplicate items can be checked for and merged on input.
- Edit Metadata – view or modify the information that Calibre stores about the selected book or books. This includes the cover image, which can be supplied from a graphics file or downloaded from the web. You can also select multiple books and change the metadata for all of them at once – for instance, selecting all books by Ian Fleming and adding ‘James Bond’ to the Series field.
- Convert Books – Calibre supports eBook conversion to and from a wide range of file formats, including plain text, HTML and word processing formats. While in the process of conversion it can ‘tweak’ the book in various ways, for instance converting plain quotes to smart quotes and adding (or removing) blank lines between paragraphs. Calibre is not intended for use as an EPUB or AZW publishing system, but it can usually do a reasonable conversion to or from these standard formats.
- View – Opens the E-Book Viewer, described above.
- Get Books – Searches major eBook sources online for a specified title, author or keyword. You can specify which sites to search. The default list includes both free and commercial sites. When a book is found, double-click it to go to the Web page where it’s offered for sale.
- Donate – Allows you to make a PayPal donation to the hard-working Calibre development team.
- Fetch News – Calibre can be used as an RSS feed reader. If you add RSS feed URLs here, then when Calibre is open those feeds will be updated and presented as ‘books’. They can be read and browsed in the Calibre E-Book Viewer. Use ‘Schedule News Download’ to browse a list of predefined feeds or define your own with ‘Add a Custom News Source’.
- Help – Opens the web-based Calibre User Manual.
- Remove Books – Removes selected books from the collection.
- Books button – An un-named button which allows you to switch to a different Calibre library. You’ll need to do this if you move your collection to a new computer, for instance, and want Calibre to re-import it.
- Save to Disk – Saves the selected book or books to a separate directory.
- Connect/Share – When working on a networked computer, Calibre supports two modes of network operation. When ‘Content Server’ is on, Calibre lists, and the books themselves, can be accessed via a web address from anywhere on the network. Apps are available for portable devices like Android tablets which can connect them up to that server directly, and make it easy to find and ‘pull’ books down from the Calibre collection. ‘Wireless Connection’ provides the same service in reverse, and allows you to ‘push’ books from Calibre to connected wireless devices. If your PC has a fixed IP number, you can open a port in your firewall and access your Calibre connection from elsewhere over the Web.
- Preferences – A wide range of customisable options, including many plugins from external sources. Others can be downloaded from the web.
Custom items from plugins that can be added to the toolbar include checking for duplicate books, estimating word or page counts, ‘tweaking’ EPUB files to improve their readability, and many others.
As well as displaying books on a PC, Calibre makes it easy to transfer books to portable devices. This can be done through wifi as described under ‘Connect/Share’ above, but also simply by plugging the device into the PC while Calibre is running. Two new icons called ‘Device’ and ‘Send to Device’ will appear on the toolbar, and a new column will be added to the table showing which books are already on the device. New books can be sent from Calibre to the device by selecting them and clicking the ‘Send to Device button. The local right-click menu will also show a new entry: ‘Send to Device’.