The MIT License is the shortest, most permissive open-source license
The MIT License lets you use, modify, and share software with almost no restrictions. You can use it in commercial products, change the code however you want, and distribute it under any terms you choose — as long as you include a copy of the original license and credit the original author. That's it. No requirement to share your changes, no requirement to use the same license for your modified version, no legal liability for the original creator if something breaks.
The license is named after the Massachusetts Institute of Technology, where it was created in the 1980s. It has become one of the most common licenses for open-source software because it removes almost all barriers to use. If you've ever installed a JavaScript library, a Python package, or a mobile app built on open-source code, you've probably encountered MIT-licensed software.
Key Takeaways
- MIT-licensed software can be used, modified, and sold in commercial products without asking permission or sharing your changes.
- The only requirement is to include the original license text and credit the original author in your code or documentation.
- The original author has no liability if the software causes problems — you use it at your own risk.
- You can relicense modified versions under any terms you want, including proprietary licenses.
- MIT is more permissive than licenses like GPL, which require you to share changes and keep derivative works open-source.
What you can and cannot do with MIT-licensed software
You can use MIT-licensed code in a closed-source commercial product without paying anyone or asking permission. You can modify it, combine it with other code, and sell the result. You can use it in a web process, a mobile app, a video game, or embedded firmware. None of these uses violate the license.
The one thing you must do is keep the license notice and the original author's name somewhere in your code or documentation. If you're distributing the software (whether as source code or compiled), the MIT License text itself must be included. If you're using it as part of a larger product, you typically need to include a notice in your documentation or in a "licenses" file that lists all open-source components.
You cannot claim you wrote the original code, and you cannot remove the original author's name from the license notice. Beyond that, the license places almost no restrictions on what you do.
How MIT compares to other common open-source licenses
The GPL (General Public License) is stricter. If you use GPL-licensed code in your project, you must release your entire project under GPL as well, and you must share your source code with anyone who receives the software. MIT has no such requirement — you can keep your modifications private and proprietary.
The Apache License 2.0 is similar to MIT but includes explicit language about patent rights and is longer. If patent protection matters to your use case, Apache may be clearer, but for most users the practical difference is small.
The BSD licenses (2-Clause and 3-Clause) are nearly identical to MIT. They allow the same uses and have the same core requirement: include the license and credit the author. The 3-Clause version adds a clause preventing use of the author's name for endorsement without permission, which MIT does not explicitly address.
| License | Commercial Use | Modify Code | Share Changes Required | Must Keep Same License |
|---|---|---|---|---|
| MIT | Yes | Yes | No | No |
| GPL v3 | Yes | Yes | Yes | Yes |
| Apache 2.0 | Yes | Yes | No | No |
| BSD 3-Clause | Yes | Yes | No | No |
Where you'll encounter MIT-licensed software
Many widely used libraries carry the MIT License. jQuery, React, Node.js, Rails, and Lodash are all MIT-licensed. So are many smaller packages in npm (JavaScript), PyPI (Python), and other package repositories. When you install a library through a package manager, you're often getting MIT-licensed code without realizing it.
Because MIT is so permissive, companies often choose it for libraries they want developers to use widely. A library author who uses MIT is saying: "I want this to be useful to as many people as possible, including people building commercial products." If the author used GPL instead, some companies would avoid the library to prevent legal complications.
What the license does not cover
The MIT License covers only the code itself, not trademarks or brand names. If you modify MIT-licensed software, you cannot use the original author's name or logo to market your version without permission. The license also does not grant you any patent rights beyond what the author already owns — though in practice, most MIT-licensed software is not patented.
The license provides no warranty. If the software breaks, causes data loss, or damages your system, the original author is not responsible. You use it at your own risk. This is standard across almost all open-source licenses, and it's why many companies run their own security audits on open-source code before using it in production.
How to comply with the MIT License in your own projects
If you use MIT-licensed code, keep the original license file in your project. If you're distributing source code, include it at the root level. If you're distributing compiled software or a web process, include a reference to it in your documentation or in a "licenses" or "credits" file that users can read.
If you modify the code, you can add your own copyright notice above or below the original one. You do not need to list every change you made — the license does not require a changelog. You do need to keep the original author's notice intact.
If you're releasing your own software under MIT, create a LICENSE file in your repository with the standard MIT License text. You can find the exact wording on opensource.org or on GitHub's license templates. Include your name and the year you first released the code.
Frequently Asked Questions
Can I use MIT-licensed code in a closed-source commercial product?
Yes. MIT allows commercial use without restriction. You can sell software that includes MIT-licensed code as long as you include the license notice and credit the original author. You do not need to share your source code or modifications.
What happens if I don't include the license notice?
Technically, you would be violating the license terms. In practice, enforcement is rare for small violations, but a company or individual could take legal action. The safest approach is to always include the notice — it takes seconds and protects you.
Can I change the MIT License terms for code I use?
No. The MIT License is set by the original author. You cannot change its terms for code you did not write. You can release your own modifications under a different license, but the original code remains under MIT.
Is MIT-licensed code safe to use in production?
MIT-licensed code can be safe or unsafe depending on the specific software, not the license itself. The license provides no warranty, so you should review the code, check for known security issues, and test it before using it in production — just as you would with any open-source software.
Can I use MIT-licensed code in a GPL project?
Yes. MIT is more permissive than GPL, so GPL-licensed projects can include MIT-licensed code. The reverse is not true — you cannot include GPL code in an MIT project without making the entire project GPL.