The MIT License Lets You Use, Modify, and Share Software With Almost No Restrictions
The MIT License is a short legal document that lets you use someone else's code however you want — including copying it, changing it, and selling it — as long as you keep a copy of the original license and the author's name attached. It is one of the most permissive open-source licenses available. The author keeps no control over what you do with the code after you receive it, and they accept no responsibility if something goes wrong.
The license is named after the Massachusetts Institute of Technology, where it was first used. Today it appears on thousands of software projects, from small utilities to major frameworks like React and Node.js. If you download code with an MIT License attached, you are free to use it in your own projects — whether those projects are free, commercial, or anything in between.
Key Takeaways
- MIT License code can be used, modified, and sold with almost no restrictions, as long as you include the original license text and author attribution in your project.
- You do not need to share your own code or make your project open-source if you use MIT-licensed code inside it.
- The license provides no warranty — if the code breaks or causes problems, the original author is not responsible.
- MIT is simpler and shorter than most other open-source licenses, making it easier to understand what you can and cannot do.
What You Can Do With MIT-Licensed Code
You can use MIT-licensed code in any project you want, for any purpose. You can modify it, combine it with other code, include it in a commercial product, and sell that product. You can also use it in a closed-source project — meaning you do not have to release your own code publicly or make it open-source.
The only real requirement is that you keep the license text and the original author's name somewhere in your project. This is usually done by copying the LICENSE file into your project folder or including the license text in a README or documentation file. Different projects handle this differently, but the goal is the same: anyone who receives your code can see who wrote the original piece and what the terms were.
What You Cannot Do
You cannot hold the original author responsible if the code causes problems. The license explicitly states that the code is provided "as is" with no warranty. If you use MIT-licensed code in your product and it breaks something, you cannot sue the original author or demand they fix it.
You also cannot remove or hide the license and author attribution. If you use the code, you must keep that information visible. Beyond that, the MIT License places almost no restrictions on you. You do not have to open your own code, you do not have to pay anyone, and you do not have to ask permission before using it.
How MIT Compares to Other Open-Source Licenses
The MIT License is more permissive than many alternatives. The GPL (General Public License), for example, requires that any project using GPL code must also be open-source and released under GPL. The Apache License is similar to MIT but includes more detailed language about patents and trademark use. The BSD License is nearly identical to MIT but has slightly different wording.
If you are choosing between licenses for your own code, MIT is the simplest choice if you want others to use your work with minimal restrictions. If you want to ensure that anyone who uses your code also releases their work as open-source, GPL is the choice. If you need more legal protection around patents, Apache might be better. The table below shows the key differences:
| License | Can Use Commercially | Can Modify | Must Open-Source Derivative Work | Length |
|---|---|---|---|---|
| MIT | Yes | Yes | No | Very short |
| GPL | Yes | Yes | Yes | Long |
| Apache 2.0 | Yes | Yes | No | Long |
| BSD | Yes | Yes | No | Very short |
Where You Will See MIT Licenses
MIT-licensed code is everywhere in software development. Popular projects like React (a JavaScript framework for building web interfaces), Node.js (a runtime for running JavaScript outside the browser), and Rails (a web development framework) all use MIT. Many smaller libraries and utilities do as well. If you download code from GitHub or another code repository, you can usually find the license by looking for a file named LICENSE in the project folder.
When you install packages or libraries through a package manager — like npm for JavaScript, pip for Python, or Composer for PHP — you can often see the license listed in the package information. Many developers choose MIT because it is simple, well-understood, and does not impose restrictions on how others use their work.
What Happens If Code Does Not Have a License
If you find code online with no license attached, you cannot assume it is free to use. Without a license, the code is automatically protected by copyright law, which means the author retains all rights. Using it without permission could be copyright infringement, even if the code is publicly visible.
If you want to use code that has no license, you should contact the author and ask for permission. They may agree to add an MIT License or another open-source license to the project, which would then let you use it legally. Many developers simply forget to add a license file, so asking is often worth the effort.
Frequently Asked Questions
Do I have to make my project open-source if I use MIT-licensed code?
No. You can use MIT-licensed code in a closed-source or commercial project without releasing your own code. You only need to include the original license and author attribution somewhere in your project.
Can I use MIT-licensed code in a product I sell?
Yes. The MIT License allows commercial use. You can sell a product that includes MIT-licensed code as long as you include the license text and author name in your distribution.
What if I modify MIT-licensed code — do I have to share my changes?
No. You can modify MIT-licensed code and keep your changes private. You only need to include the original license and author attribution with your project.
Is the author responsible if MIT-licensed code breaks my project?
No. The MIT License includes a disclaimer stating the code is provided "as is" with no warranty. If the code causes problems, the author is not liable.
Where do I find the MIT License text to include in my project?
The full MIT License text is publicly available and short enough to copy by hand. Most projects store it in a file named LICENSE at the root of the project folder. You can also find the standard text on opensource.org or GitHub's license templates.