From Shopp Documentation

Shopp was designed to provide bolt-on e-commerce functionality to WordPress-driven blogs/websites. It has been carefully crafted to provide easy online store management to merchants that may be somewhat tech-ignorant while being flexible enough for designers and developers to customize nearly every aspect of the shopping experience without resorting to hacking the core code.

Features

There certainly are other WordPress e-commerce solutions. Each with their own strengths and weaknesses. Shopp's experience is unique in both the shopping experience and in the administration of an online store.

It works "out-of-the-box" with most WordPress themes (though quality of the default shopping experience may vary depending on the quality of the theme). A template system with custom programming tags gives Shopp the ability to be customized to perfectly integrate with any theme.

A super-human effort has been made to design cutting-edge administration interfaces that hide most of the complexity (where possible), but reveal advanced features and functionality on an as needed basis.

License

Shopp is a commercial open-source project released under the GPLv3 and is built as a plugin specifically for WordPress (v2.5 or newer) on web hosting systems running PHP (v5.2 or newer) and MySQL (v4 or newer).

For more details about the GPLv3 license and why Shopp uses it, read about the Shopp License.

Commercial Open-Source Project

Although Shopp uses open-source code, the project is a commercial venture of Ingenesis Limited, owned and operated by Jonathan Davis. Shopp's open-source nature means that the code is openly distributed and available for the owner to run, copy, distribute, study and improve. It is technically considered free (relating to freedom, as in free-speech) software. Shopp is, however a commercial project, meaning Ingenesis is looking to make some money in the process.

To protect this commercial interest, Ingenesis Limited sells an activation key that gives the buyer unlimited access to major point-release upgrades (meaning all releases under 1.x), discounted upgrade prices for major releases (meaning upgrades from 1.x to 2.0 for example), bug fix and security enhancement patches.

So what if you don't buy Shopp?
Users that get a copy of Shopp (from, say, a friend that bought it) will be able to use the plugin unrestricted. There is no safeguard against using a copied version. However, they will only have access to upgrades that their "source" provides and will be reliant upon them for upgrades. They will also be limited to using the free support resources via the forums and the documentation wiki. They will not get premium support access, they will not have access to important security and bug fix patches and point release upgrades via the WordPress automatic plugin upgrade system. We hope these incentives, along with the Ingenesis Limited commitment to quality software development, honesty, integrity, openness and software freedoms will encourage users to purchase an activation key and support continued development of this e-commerce platform.

Shopp is a venture into the relatively blurry realm of paid-for open-source software and is even more unique in that it is among a handful of commercial plugins for WordPress. It is with great hope and optimism that Shopp can become a model for how to approach commercial open-source WordPress plugins without being necessarily evil about it. In other words, help us help you.

About the Author

Shopp was created by Jonathan Davis (Jon) of Ingenesis Limited. At Ingenesis, Jon is a consultant for custom web design and development. He started working on the Internet in 1996 at a small-town (now defunct) Internet Service Provider. During his tenure there, he honed his programming and design skills. In that time, he has been involved in the development and launch of over 60 web projects from small-business websites to large community sites of which many have won industry marketing awards.

Jon is available (for hire) to create a fully custom Shopp implementation according to your specs and requirements. Find out how to get in touch on his blog.