MIT License
em-eye-TEE LY-sens
A permissive open source license that allows anyone to use, modify, and distribute the software with minimal restrictions.
The MIT License is the most popular open source license in the world. It says: do whatever you want with this code, just keep the copyright notice and do not hold us liable. That is essentially the entire license in two sentences.
It is called permissive because it places almost no restrictions on what you can do with the software. You can use it commercially, modify it, distribute it, sublicense it, and include it in proprietary products. The only requirement is that you include the original copyright notice and license text.
React, Node.js, jQuery, Rails, and thousands of other projects use the MIT License. Developers choose it because it maximizes adoption. There is no copyleft clause forcing derivative works to also be open source, which makes MIT-licensed code safe to include in commercial products. The Apache License is a similar permissive option with added patent protections. Open source license compliance tools track these obligations automatically.
Examples
A startup uses an MIT-licensed library in a commercial product.
The startup includes the library's copyright notice in their product's third-party licenses file. They are free to modify the code and ship it as part of their paid SaaS product.
An open source maintainer chooses a license.
The developer wants maximum adoption and does not care if companies profit from their code. They choose MIT because it is simple, well-understood, and does not create legal friction for users.
A legal team audits dependencies.
The audit finds 200 MIT-licensed packages. The legal team is not concerned because MIT is the lowest-risk open source license. They flag three GPL-licensed packages for further review.
Frequently asked questions
Can I use MIT-licensed code in commercial software?
Yes. The MIT License explicitly permits commercial use. You must include the copyright notice and license text, but you can use, modify, and sell products that contain MIT-licensed code.
What is the difference between MIT and Apache licenses?
Both are permissive. Apache adds an explicit patent grant (protecting users from patent claims) and requires documenting changes to the source code. MIT is simpler but does not address patents.
Related terms
A permissive open source license that includes an explicit patent grant and requires attribution for modifications.
A copyleft open source license that requires derivative works to also be distributed under the GPL.
The practice of tracking and fulfilling the legal obligations of all open source software used in a product.
A source-available license that restricts commercial use for a set period before converting to a fully open source license.
Want the complete playbook?
Picks and Shovels is the definitive guide to developer marketing. Amazon #1 bestseller with practical strategies from 30 years of marketing to developers.