Scriptalicious Blog

There are thousands of free PHP scripts to speed up development. Established PHP frameworks and JavaScript libraries abound. It's expensive to reinvent the wheel, and pointless besides. But when is it legal to use free code in your commercial apps, and how will it affect your project?

There are three important things to consider before using any free script in your commercial sites, software products, Web apps, and services.

1. Is use allowed for all commercial purposes?
2. Must you provide credit, display copyrights, or any other kind of attribution and where?
3. What effect does implementation have on other source code?

Most open source projects require that you release all changes or enhancements to their library back to the community. This is why commercial implementation can really improve an open source project. But some free projects can be more “sticky” than others, so check the license for all of these details.

Fortunately, most projects use a standard free software license, sometimes with small modifications. Some projects even offer multiple licenses so you can pick the best one for your project.

The GNU GPL license is an extremely popular free software license, but is considered a non-permissive license. GPL software requires that derivative works be held under the same license. A family of permissive licenses such as the BSD and MIT licenses allow you to create derivative works with more restrictive copyrights and generally without having to release your open software for free.

For commercial projects, permissive licenses like BSD and MIT licenses are usually acceptable. Attention should be paid to any code used for bridging with your own software. The more loosely coupled they are the easier it will be to maintain a separate license, and also to manage and contribute work back to the free project.