Kristo Vaher

GNU GPL Logo

Having worked as a software developer for handful of years, I have had to both use and deal with software licenses, both free and not. But of all the various software licenses out there, the GPL (and its sibling, LGPL) have been of most notable use. This says quite a bit about the licenses, since GPL and LGPL have laid a large foundation to modern software development. In this post I shall be discussing my experiences with GPL and LGPL from the perspective of a web developer, both when using other software as well as when developing new software myself.

GPL basically states the following:

• Source code of software must be free
• Must retain license notice
• Can sell without restrictions
• GPL modifications and derivations must be covered under the same license.

One of the things often misunderstood is the first point in the list. GPL source code being ‘free’ does not mean that a third party does not have to pay for it. However it does mean that if third party does pay for it, then they retain the right to sell it to another party or release it as free (listed as ‘can sell without restrictions’ in the list). This is often an issue with many clients, who think that just because their software is covered by GPL, that someone else can take and start using their software just by wanting to do so.

The fourth point is most relevant to software developers, since this strongly affects what open source software can developers use as part of their (often clients ordered) projects. For example, a company cannot create a copyrighted software and link a GPL library or application to that software, without the copyright not becoming invalid anymore. Should such a linking occur, the entire software must be covered by GPL and if sold, the buyer has the right for both source code and redistribution rights, as long as the license is not broken. This is very important in web development, especially as some companies like to encrypt their source code of clients project, so they cannot be edited by the client.

What helps here is the aforementioned Lesser GPL, or LGPL. Similar to GPL in other ways, LGPL allows linking without enforcing the same license. A lot of software libraries and classes utilize LGPL, since this encourages wider adoption rate of the software or library. In simpler terms, this means that if a copyrighted software wants to use free software released under LGPL, for example using TinyMCE (a web based HTML editor) as part of a Content Management System application, then this can be achieved without requiring to abolish the original copyright. If TinyMCE was covered by GPL, then the Content Management System cannot be copyrighted and can be freely shared and redistributed by client.

This creates often interesting dilemmas when a developer decides to publish their own software as well. In one way, LGPL is less than perfect in that suddenly this can also be used by tightly coupled and copyrighted works for which companies ask heavy price for without the author getting any recognition beyond the original license being included in the software. However an LGPL is preferred by many developers for the main reason that we simply live in a world where we have to work on copyrighted projects and ourselves know the pains of having to reject part of open software simply because it is not covered by LGPL (or similar) license. LGPL also allows the developer to gain more recognition for the same reasons, especially if the released software is relatively small.

GPL is preferred by developers when creating something larger than a library or a class. It is not very common for large infosystems or other web based software to be released without GPL (WordPress and MediaWiki are both GPL). Since a lot of times such a software will be used independently from other applications, benefits of using LGPL fade in comparison, since majority of clients who end up using this software, will not be doing so by having it linked tightly with another infosystem or software.

I think that copyleft licenses, such as GPL and LGPL have had a major impact on software development industry and are a foundation to a lot of new media solutions all of us use today. Internet solutions are already relatively open source friendly platform, in a way that source codes are rarely compiled. Thus it has been the perfect area for such copyleft licenses to thrive in and this trend is unlikely to change anytime soon.