What the MIT License Means and How It Works

The MIT License is one of the shortest and most permissive open-source licenses

The MIT License is a legal agreement that lets you use, modify, and share software written by someone else, with almost no restrictions. The person who wrote the software keeps their name on it, but they give up the right to control what you do with it. You can use it in your own projects, sell software that includes it, change the code, or keep your changes private — the MIT License allows all of this.

The license is named after the Massachusetts Institute of Technology, where it was created. It is one of the most common licenses you will see on code shared on GitHub and other platforms where programmers publish their work. The entire license is about 170 words long, which is why it is so straightforward compared to other legal agreements for software.

Key Takeaways

The MIT License lets you use, modify, and share software freely, including in commercial projects, with almost no restrictions.
You must keep the original copyright notice and license text with the software, even if you change the code.
The original author is not responsible if the software breaks, causes problems, or does not work the way you expected.
You can use MIT-licensed code in closed-source software you sell or keep private, unlike some other open-source licenses.
If you find MIT-licensed code in a project, you need to include the license file in your own distribution of that software.

What you can and cannot do with MIT-licensed software

The MIT License gives you four main rights: you can use the software for any purpose, modify the code, distribute copies, and distribute your modified versions. There are no restrictions on whether you use it for personal projects, commercial products, or anything in between. You do not have to pay anyone, ask permission, or tell the original author what you are doing.

The only real requirement is that you keep the copyright notice and the license text attached to the software. If you distribute the software — whether you changed it or not — the license file must come with it. This protects the original author by making sure they get credit and that anyone who receives the software knows what rights they have.

You cannot hold the original author responsible if the software does not work, causes damage, or fails to do what you expected. This is called a "no warranty" clause. The author gives the software away and makes no promises about how well it works or whether it is safe to use.

How the MIT License differs from other open-source licenses

Some open-source licenses require you to share your own changes with the world. The GPL license, for example, says that if you modify the software and distribute it, you must release your modified version under the same GPL license. This means your changes become open-source too. The MIT License has no such requirement — you can modify the code and keep your changes completely private.

Other licenses, like the Apache License, are similar to MIT but include extra clauses about patents and how to handle trademark use. The MIT License skips these details and stays minimal. This makes MIT simpler to understand but also means it does not address some edge cases that other licenses cover.

The key difference is that MIT is permissive, meaning it gives you the most freedom to do what you want. Licenses like GPL are copyleft, meaning they require you to pass those same freedoms along to anyone who gets your code. If you want to use code in a closed-source product you sell, MIT is usually the easiest license to work with.

Where you will see the MIT License in practice

Many popular software libraries and frameworks use the MIT License. If you download code from GitHub, npm (a repository for JavaScript code), or PyPI (a repository for Python code), you will often find MIT-licensed projects. Some well-known examples include jQuery, Rails, Node.js, and Lodash — all widely used by developers.

When you use an MIT-licensed library in your own project, you are responsible for including the license file. Most package managers handle this automatically — when you install a library, the license comes with it. If you are distributing software that includes MIT-licensed code, you need to make sure the license file is in your distribution so anyone who receives your software can see it.

What to do if you find MIT-licensed code in your project

If you are building software and you use a library or code snippet that is MIT-licensed, you need to keep the license file with your project. The exact location depends on how you are distributing the software. If you are publishing on npm or PyPI, the license usually goes in a file called LICENSE or LICENSE.txt at the root of your project folder.

If you are distributing software to users, include the license file in your installation package or documentation. Many projects create a LICENSES folder that lists all the open-source licenses for code they use. This is especially important if your project uses multiple libraries with different licenses.

You do not need to ask the original author for permission or notify them that you are using their code. The MIT License is a blanket agreement that covers anyone who wants to use it. Just make sure the license text stays with the code, and you are following the agreement.

Frequently Asked Questions

Can I use MIT-licensed code in software I sell?

Yes. The MIT License allows commercial use. You can include MIT-licensed code in a product you sell, charge money for it, and keep your own code closed-source. You only need to include the original license file and copyright notice with your distribution.

Do I have to release my changes if I modify MIT-licensed code?

No. Unlike some open-source licenses, MIT does not require you to share your modifications. You can change the code and keep your changes private. You still need to include the original license and copyright notice.

What if the MIT-licensed code breaks my software?

The license includes a "no warranty" clause, which means the original author is not responsible for problems the code causes. If the software fails or causes damage, you cannot sue the author. This is why you should test any code you use before relying on it in production.

Can I remove the copyright notice from MIT-licensed code?

No. The license requires you to keep the copyright notice and license text with the software. Removing it violates the agreement. The notice must stay even if you modify the code.

Is MIT-licensed code truly free to use?

Yes, it is free in the sense that you do not pay money and you do not need permission. The only requirement is keeping the license and copyright notice attached. There are no hidden fees or restrictions on how you use it.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.