How to Choose an Open Source License (2026)
Choosing a license is one of the most important decisions for an open source project, yet most developers spend less than a minute on it. The license determines how others can use, modify, and distribute your code. No license means no permission — your code is under exclusive copyright by default, and no one can legally use it.
- Compare MIT, Apache 2.
- Why You Need a License.
- Covers permissive licenses: mit, bsd, isc.
- Covers copyleft licenses: gpl.
- Covers quick license comparison.
Why You Need a License
Without a license file, your code is under exclusive copyright. Even if it is on a public GitHub repository, no one has legal permission to use, copy, modify, or distribute it. Public does not mean free to use.
Adding a LICENSE file takes 30 seconds and removes all ambiguity. It tells users and companies exactly what they can and cannot do with your code. This matters because many companies have legal departments that check licenses before using open source software.
Once you publish code under a license, you cannot retroactively revoke permission for existing versions. You can change the license for future versions, but anyone who obtained code under the original license retains their rights. Choose carefully.
Permissive Licenses: MIT, BSD, ISC
MIT is the most popular open source license. It allows anyone to use, copy, modify, merge, publish, distribute, sublicense, and sell your software with one condition: include the original copyright notice and license text. That is it.
-webkit-backdrop-filter alongside backdrop-filter for Safari support. Without the prefix, the effect is invisible to roughly 25% of mobile users.BSD 3-Clause is similar to MIT with an additional clause preventing others from using your name to endorse derivative products. The practical difference from MIT is negligible for most projects.
ISC is even simpler than MIT — it is functionally equivalent but uses clearer language. It was written by the Internet Systems Consortium and is used by npm and many Node.js packages. If you want the simplest possible permissive license, use ISC.
Copyleft Licenses: GPL
GPL (GNU General Public License) requires that derivative works also be released under GPL. If someone modifies your code and distributes it, they must release their changes under the same license. This ensures the code and its derivatives remain free forever.
backdrop-filter inside a position: fixed element can cause severe scroll performance issues. Test thoroughly on real iOS devices.This is a philosophical choice. GPL supporters believe software freedom should propagate. Critics argue it restricts how the code can be used in commercial products. Many companies cannot use GPL code in proprietary products.
LGPL (Lesser GPL) is a middle ground that allows linking to your library without requiring the entire application to be GPL. This is common for libraries that want broad adoption while keeping their own modifications open.
Quick License Comparison
MIT: Maximum freedom. Anyone can do anything. Only condition: include the license text. Best for libraries and tools you want widely adopted.
Apache 2.0: Like MIT but adds explicit patent rights and requires documenting changes. Preferred by companies because the patent clause prevents patent trolling.
GPL 3.0: Strong copyleft. Derivative works must also be GPL. Ensures the code and all modifications remain free forever. Limits commercial use in proprietary products.
Unlicense: Dedicates your code to the public domain. No conditions at all. Some jurisdictions do not recognize public domain dedications, making this legally ambiguous in some countries.