MIT vs GPL: Which Open Source License Should You Choose?
6minChoosing a license is the first legal decision every open source project makes, and it is the one people get wrong most often. Pick MIT and you can never close the door later: the code you released is out there under terms you cannot revoke. Pick GPL and you are imposing obligations on every downstream user.
The real question is not "which is more popular": it is what you want to happen to your code after it leaves your repository.
MIT
Permissive. Anyone can use, copy, modify, and redistribute: even in closed-source commercial products. They only must keep your copyright notice.
GPL-3.0
Copyleft. Anyone can use and modify your code, but derivative works must also be released under the GPL with source available.
| Aspect | MIT | GPL-3.0 |
|---|---|---|
| Commercial use | Allowed with no obligations | Allowed, but derivative work must stay GPL |
| Source disclosure | Not required | Required for anyone who receives the software |
| SaaS / cloud use | Allowed silently | GPL-3.0 closes the loophole: network users must get source |
| Patents | No explicit patent grant | Explicit patent grant and retaliation clause |
| Mix with proprietary code | Yes: standard in SDKs and libraries | No: proprietary code cannot link against GPL libraries |
| Contributor experience | Sign nothing, minimal friction | Same-day contribution is easy, but projects often add a CLA anyway |
| Default in ecosystems | The default for npm, PyPI, and most frontend libraries | Common in Linux/embedded, rarely for libraries |
Pick MIT when you want maximum adoption: SDKs, libraries, and anything you hope other companies embed. Pick GPL-3.0 when you care more about guaranteeing the code stays free than about adoption, or when you ship server software and want network users to share back. There is no "safer" choice: only the one that matches your goal.
- •Believing MIT lets others "steal" your code. It does not: it grants a license you chose, and attribution is still required.
- •Choosing GPL because it sounds stronger, then wondering why no company will touch your library.
- •Copying a license file from another project without checking it matches the version you say it is.
- •Releasing code without a license at all: that makes it all-rights-reserved, which is the opposite of open source.