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MIT License

The MIT License is the most popular open source license in the world. Its simplicity and permissiveness have made it the default choice for countless projects.

At a Glance

Attribute Value
SPDX Identifier MIT
Type Permissive
Patent Grant No
Copyleft No
License Length ~170 words

What It Allows

  • Commercial use
  • Modification
  • Distribution
  • Private use
  • Sublicensing

What It Requires

  • Include copyright notice
  • Include license text

What It Prohibits

  • Holding authors liable
  • Using authors' names for promotion (implied)

The Full Text

The MIT License is short enough to read in full:

MIT License

Copyright (c) [year] [fullname]

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

Key Points

Maximum Simplicity

MIT imposes only one real obligation: include the copyright notice and license text when you redistribute the code. That's it. There's no requirement to share source code, no patent considerations, no compatibility headaches.

No Patent Grant

Unlike Apache 2.0, MIT says nothing about patents. If a contributor holds a patent covering the code, you receive no explicit license to that patent. For most projects this is theoretical, but it's a consideration for enterprise adoption.

Compatible With Everything

MIT-licensed code can be:

  • Included in proprietary software
  • Relicensed under different terms
  • Combined with code under virtually any other license

This makes MIT code extremely easy to incorporate into other projects.

When to Use MIT

MIT is a good choice when:

  • You want maximum adoption
  • You don't care if others use your code in proprietary products
  • Simplicity is a priority
  • You're building libraries, utilities, or tools

When to Consider Alternatives

  • If you want improvements to come back to the community → consider copyleft
  • If patent protection matters → consider Apache 2.0
  • If you want no attribution requirement → consider Unlicense or CC0

Notable Projects Using MIT

  • React
  • Vue.js
  • Ruby on Rails
  • .NET Core
  • jQuery
  • Node.js
  • Electron