A one stop solution to all your e-book needs. It is free, open source and cross-platform in design and works well on Linux, OS 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 e-book reader sync features and an integrated e-book viewer.

Design philosophy

I come from the Unix world, which means calibre is architected in little pieces each with its own command line interface which means that each piece of functionality is reusable not just in python programs but in any software. In fact adding complete support for converting any new ebook format to calibre requires the writing of only two converters format->html and html->format as well as a metadata reading/writing tool. All the other features of calibre will work automatically with these three converters in place. Similarly, writing a device driver requires very little work. You basically have to implement a well-defined interface (interface.py). Once you do that, your device will have full support in calibre.
Adding support for new Input/Output formats

Calibre is written primarily in Python with a few C extension modules. So you have to contribute plugins in either Python or C/C++. Because of its modular design and support infrastructure, adding support for new formats is simple:

* A new input format
o A module that can read metadata from files in the input format.
o A module that can convert the input format into one or more HTML files.

* A new output format
o A module that can write metadata to files in the output format.
o A module that can convert a sequential list of HTML files into a file in the output format.

If you create a plugin to do this, just let me know, and I will take care of integrating it into the calibre code base.
Adding support for new devices

You have to create a device driver that implements the DeviceInterface defined in interface.py. You should be able to lift a lot of code from the existing drivers in the calibre.devices package.
Browsing the source code

The source code can be browsed online in launchpad. If you're interested in development, you can submit patches as outlined below. Also consider joining the calibre-devs team and subscribing to its mailing list.
Setting up the development environment.

If you are on Linux, setting up a development environment is very simple and is outlined below. If not, there is a VMWare Appliance with a fully-setup development environment calibre-gentoo.7z. Passwords are the same as usernames. Once you have it running, log in as kovid and start up Eclipse; it has the calibre project already setup. Update the code from bzr and run make as shown below. Submit patches and if you want to do a lot of development talk to me about getting commit access to the bzr repository.
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