GPL License
General Public License (GNU GPL) - The most widely used free software license
The GPL (General Public License), also known as GNU GPL, is the most used free software license. It was created by Richard Stallman for the GNU Project (Free Software Foundation).
It allows the software to be freely used, modified, and redistributed by anyone. WordPress also comes with the GPL license, which means that WordPress is open-source software that can be used, modified, and extended by anyone.
GPL provides the core basic values that the project believes in.
Freedom to Use
Anyone can download and run the software for any purpose.
Freedom to Study
Anyone can modify/edit the software to suit their needs.
Freedom to Share
Anyone can redistribute free copies of the software.
Freedom to Improve
Anyone can distribute modified versions of the software.
GPL License Questions Answered
1. What is copyleft?
Copyright is a law that restricts the right to use, modify, and share creative works without the permission of the owner.
When an author releases a program under a copyleft license, they make a claim on the copyright of the work and issue a statement that other people have the right to use, modify, and share the work as long as the reciprocity obligation is maintained.
This means that any software that is written based on any GPL must be released as open-source. If any software uses any GPL open source component, it has to be required to release its full source code and all of the rights to modify and distribute the entire code.
2. Can you sell GPL Products?
Yes, the GPL license allows selling the original as well as the modified products. However, free software is referred to as free in terms of freedom to use not in terms of price. As Richard Stallman explained, free software means free as in "free speech," not free as in "free beer."
3. Is GPL safe?
Yes. GPL doesn't have anything to do with the source code security. It's just a license that governs its usage and distribution.
4. Does the GPL license require the author to release the modified source code?
Under the GPL License, it requires you to release the modified source code only if you release the modified program. If you have modified a program's code for personal use, then there's no need to release it.
GPLv2 vs GPLv3
There has always been some confusion regarding the difference between GPLv2 & GPLv3. Here are the key differences:
GPLv2
- Language considered very US-centric
- Less explicit about when reciprocity obligation is triggered
- Limited compatibility with other licenses
- Does not address the "ASP loophole"
GPLv3
- Language modified to work well with international laws
- More clarity about when reciprocity obligation is triggered
- Improved compatibility with other licenses
- Addresses the "ASP loophole" (with Affero license)
- Allows developers to add local disclaimers
- Better suited for global usage
What changed in GPLv3?
The FSF tried to add more clarity to GPLv3 as to when the reciprocity obligation is triggered. The FSF even wrote a new GPL license, the Affero license, to address the "ASP loophole".
In addition, the FSF decided to improve the compatibility of the GPLv3 with other licenses. To combine two codes into a larger work, both applications must permit it. If those rights are imparted by both the programs' licenses, they are compatible. By making the GPLv3 more compatible, the FSF increased development options.
The third difference between the two versions is that the GPLv3 was written in an effort to increase usage globally. The language used in GPLv3 to describe the license rights was modified to ensure that international laws will interpret it as the FSF intended, unlike the language used in GPLv2. GPLv3 also permits developers to add local disclaimers, which also helps to grow its usage outside the US.
GPL License Terms and Conditions
- It doesn't allow claiming patents or copyright on the product.
- It requires displaying a copyright notice, disclaimer of warranty, intact GPL notices, and a copy of the GPL.
- You are not allowed to change the license or add some additional terms & conditions.
- You are bound to release the source code and all of the rights to modify and distribute the entire code if you distribute modified versions.
Important Disclaimer
The owner of this site is not a lawyer. That means you should not interpret this as legal advice of any kind. Information is provided on an as-is basis. For legal advice regarding software licensing, please consult a qualified attorney.
