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What are the 2 Most Common Software Licenses?

Published in Software Licenses 3 mins read

The two most common software licenses are the Apache License and the MIT License. These highly popular open-source licenses are widely adopted across numerous software projects due to their permissive nature.

Understanding Common Software Licenses

As of 2022, among the most popular open-source licenses are the Apache License, the MIT License, and the GPL (GNU General Public License). While all three are extensively used, the Apache and MIT licenses are particularly prevalent given their flexibility and minimal restrictions.

Permissive Licenses: Apache and MIT

Both the Apache License and the MIT License are classified as "permissive" licenses. This means they impose minimal restrictions on how the software can be used, modified, and distributed. Developers and companies often favor these licenses for their flexibility, allowing for easy integration into proprietary software without requiring the release of derivative source code.

  • Apache License: This permissive free software license, issued by the Apache Software Foundation, allows users to freely use, modify, and distribute Apache-licensed software. Key requirements include preserving copyright notices and disclaimers. A notable feature is its explicit patent grant, which helps protect contributors and users from patent claims related to their use of the software.
  • MIT License: Known for being one of the shortest and simplest permissive licenses, the MIT License grants users broad rights. These rights include the ability to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the software. The primary condition is that the original copyright and permission notice must be included in all copies or substantial portions of the software. Its straightforwardness and flexibility contribute significantly to its immense popularity across a vast array of projects.

Copyleft Licenses: The GPL

In contrast to permissive licenses, "copyleft" licenses, such as the GPL (GNU General Public License), are designed to ensure that all modified versions of the software remain free. This means if you distribute software based on a GPL-licensed project, you are generally required to distribute your modifications under the GPL as well, making the corresponding source code available. This mechanism ensures the "freedom" of the software propagates through its derivatives.

Public Domain Software

Beyond specific licenses, some software exists in the public domain. When software is in the public domain, it signifies that the owner's copyright has been extinguished. Consequently, anyone may use the work with no copyright restrictions whatsoever, offering the ultimate freedom in terms of usage and distribution.

Key Differences Between Apache and MIT

While both are permissive, there are subtle yet important distinctions between the Apache and MIT licenses that can influence a developer's choice:

Feature MIT License Apache License 2.0
Requirements Primarily requires the inclusion of the copyright and permission notice. More extensive requirements, including copyright, patent, trademark, and attribution notices. Also mandates retaining disclaimers.
Patent Grant Does not include an explicit patent grant. Includes an explicit grant protecting against patent claims from contributors.
Liability Explicitly disclaims liability. Disclaims liability and warranty.
Simplicity Very concise and easy to understand. More verbose, featuring additional clauses and legal language.

This table helps illustrate the practical differences for developers deciding between these two widely adopted choices.

For more comprehensive information on various software licenses and their implications, you can refer to the Wikipedia page on Software Licenses.