GPL vs. MPL

Attribute	GPL	MPL
License Type	Copyleft	Weak Copyleft
Compatibility with other licenses	Less compatible	More compatible
Derived Works	Must be under GPL	Can be under different license
Modifications	Must be open-sourced	Can be kept private

Introduction

When it comes to open-source licenses, two popular choices are the GNU General Public License (GPL) and the Mozilla Public License (MPL). Both licenses have their own unique attributes and are widely used in the software development community. In this article, we will compare the key features of GPL and MPL to help developers make an informed decision when choosing a license for their projects.

License Scope

The GPL is a copyleft license, which means that any derivative works must also be licensed under the GPL. This ensures that the source code remains open and freely available to the community. On the other hand, the MPL is a weak copyleft license, which allows developers to combine MPL-licensed code with proprietary code without requiring the proprietary code to be open-sourced. This gives developers more flexibility in how they use MPL-licensed code.

Compatibility

One important consideration when choosing a license is compatibility with other licenses. The GPL is known for its strict copyleft provisions, which can make it incompatible with some other licenses. For example, GPL-licensed code cannot be combined with code licensed under the Apache License 2.0. On the other hand, the MPL is designed to be more compatible with other licenses, making it easier for developers to incorporate MPL-licensed code into their projects without running into licensing conflicts.

Distribution Requirements

Another key difference between GPL and MPL is their distribution requirements. The GPL requires that any modifications to GPL-licensed code must be made available to the community under the same license. This ensures that the source code remains open and accessible to all users. In contrast, the MPL only requires that any changes to MPL-licensed code be made available to the original author, giving developers more control over how their modifications are distributed.

Patent Grants

One unique feature of the MPL is its patent grant provision, which grants developers a license to any patents held by the original author of the MPL-licensed code. This can help protect developers from patent infringement lawsuits and ensure that they can use the code without fear of legal repercussions. The GPL does not include a similar patent grant provision, which can make it more challenging for developers to navigate the complex landscape of software patents.

Community Support

Both the GPL and MPL have strong communities of developers who support and advocate for the use of their respective licenses. The Free Software Foundation (FSF) is a prominent advocate for the GPL and provides resources and guidance to developers who choose to license their code under the GPL. Similarly, the Mozilla Foundation supports the use of the MPL and provides tools and resources to help developers understand and comply with the terms of the license.

Conclusion

In conclusion, the GPL and MPL are both popular open-source licenses with their own unique attributes. The GPL is a strict copyleft license that ensures the source code remains open and freely available, while the MPL is a weak copyleft license that offers more flexibility in how code can be used. Developers should carefully consider the scope, compatibility, distribution requirements, patent grants, and community support of each license before choosing the one that best fits their project's needs.