An open source licenses comparison across MIT, Apache 2.0, GPL, and BSD comes down to two questions: does the license require you to release your own source code (copyleft), and does it grant an explicit patent license alongside the copyright grant? This mit license open source comparison covers Apache 2.0, GPL, and BSD side by side so you can see exactly where each one lands on both questions. MIT and BSD are permissive with no patent clause. Apache 2.0 is permissive with an explicit patent grant. GPL is copyleft, meaning derivative works generally must be released under the same terms. Knowing which bucket a dependency falls into is most of what you need for a practical compliance decision.
MIT License: Maximum Simplicity
The MIT license open source developers choose most often is also the simplest one to comply with. The MIT License is two paragraphs: do what you want with this code, keep the copyright notice, no warranty. It has no patent clause, no copyleft obligation, and is compatible with essentially everything, which is why it remains the most widely used license on GitHub and across the npm and PyPI ecosystems. Its simplicity is also its main limitation — it says nothing about patents, which some contributors (and legal teams at larger companies) find insufficiently protective for patent-heavy technology.
BSD License(s): MIT's Close Cousin
The BSD license family (2-clause and 3-clause being most common) is functionally similar to MIT: permissive, no copyleft, minimal obligations. The 3-clause variant adds a non-endorsement clause preventing use of the original authors' names to promote derivative products without permission. Like MIT, BSD carries no explicit patent grant, which is the main practical difference from Apache 2.0.
Apache License 2.0: Permissive Plus Patent Protection
Apache 2.0 is permissive like MIT and BSD but adds two things they lack: an explicit patent grant (contributors license any patents they hold that are necessarily infringed by their contribution) and a patent retaliation clause (if you sue anyone for patent infringement over the covered code, your license terminates). This makes Apache 2.0 a common choice for larger companies and foundation-backed projects, since it reduces patent litigation ambiguity that MIT and BSD simply don't address. It does require preserving notices and stating changes made to the code, a slightly heavier obligation than MIT/BSD but still far short of copyleft.
GPL: Copyleft, With Teeth
The GNU General Public License requires that derivative works — code that incorporates or links against GPL code in ways the license defines as creating a "derivative work" — be released under the same GPL terms if distributed. This is the defining feature of copyleft: the license propagates. GPLv3 also added explicit patent grant and anti-tivoization provisions (preventing hardware restrictions on running modified software) that GPLv2 lacked. The practical consequence for a company evaluating a GPL dependency: using it inside a proprietary product you distribute can obligate you to release your own source, which is why many commercial software policies flag GPL dependencies for legal review by default, and its stricter cousin, the AGPL, extends that trigger to network use rather than just distribution.
Side-by-Side: What Actually Differs
| License | Copyleft | Patent Grant | Attribution Required | Common Use |
|---|---|---|---|---|
| MIT | No | No | Yes (notice) | npm packages, small libraries |
| BSD (2/3-clause) | No | No | Yes (notice) | Systems software, academic code |
| Apache 2.0 | No | Yes | Yes (notice + changes) | Enterprise and foundation projects |
| GPL (v2/v3) | Yes | v3 only | Yes | Linux kernel, many desktop apps |
How Should You Use This in Practice?
For a compliance program, the license category matters more than memorizing exact clause text: permissive-no-patent (MIT/BSD), permissive-with-patent (Apache 2.0), and copyleft (GPL family, plus the stronger AGPL) are the three buckets that drive most real decisions. When teams ask which permissive option to default to, an open source MIT license is usually the answer — it imposes the fewest obligations of any option on this list. Automated license scanning across your dependency tree turns this from a manual audit into a continuous check, flagging copyleft dependencies for review before they ship rather than after a legal audit finds them.
FAQ
Can I mix MIT and Apache 2.0 code in the same project?
Yes. Both are permissive and broadly compatible with each other and with proprietary code, though Apache 2.0's patent and notice requirements carry forward and should be preserved in your own license file.
Is GPL code always incompatible with proprietary software?
Not always incompatible, but it's restrictive: using GPL code in ways that create a derivative work generally requires releasing your own source under GPL if you distribute the result. Static vs. dynamic linking and how you invoke the code matters here, and this is genuinely fact-specific enough that legal review is warranted for real cases.
What's the real difference between BSD and MIT?
Practically minimal. Both are short, permissive, and require attribution. The 3-clause BSD variant adds a non-endorsement clause that MIT doesn't have; otherwise the licenses grant nearly identical permissions.
Why does the Apache license matter for enterprise adoption?
Its explicit patent grant and retaliation clause give companies more legal certainty around patent risk than MIT or BSD provide, which is part of why many enterprise and foundation-backed projects (Kubernetes, Apache projects themselves) choose it.