Choosing an open-source license for your project is a crucial step in sharing your work with the world. A license dictates how others can use, modify, and distribute your code, setting the groundwork for collaboration and protection.

With so many options, including permissive licenses like MIT and copyleft licenses like GPL, each offering different freedoms and restrictions, it’s essential to understand their distinctions. This guide breaks down the most popular open-source licenses—MIT, Apache 2.0, GPL, LGPL, and CC0—so you can make an informed choice that aligns with your goals and vision for your project.

MIT License

  • Permissions: Allows anyone to use, modify, and distribute the code, even in proprietary (closed-source) projects.
  • Conditions: Requires including the original license text and copyright notice with the code.
  • Limitations: Provides no warranty; the author is not liable for damages.
  • Best For: Projects where you want minimal restrictions and don’t mind others using the code in both open and closed-source projects.

Summary: Very permissive; widely used due to simplicity and flexibility.

2. Apache License 2.0

  • Permissions: Allows use, modification, and distribution, including in proprietary projects.
  • Conditions: Requires license and copyright notice retention, includes patent rights to users, and requires changes in files to be marked.
  • Limitations: Disclaims warranties and liability.
  • Best For: Projects needing patent protection or for contributors concerned about patent litigation.

Summary: Permissive with added patent protection; popular in corporate and commercial projects.

3. GNU General Public License (GPL) 3.0

  • Permissions: Users can run, study, share, and modify the code.
  • Conditions: Copyleft license—any derivative works must also be licensed under GPL. Modifications must be made available when distributing the software.
  • Limitations: Disclaims warranties; users cannot place additional restrictions on rights granted by GPL.
  • Best For: Projects intended to stay open-source and for users who want to enforce that any derived work remains open-source.

Summary: Strong copyleft; ideal for projects aimed at ensuring all derivatives remain open-source.

4. GNU Lesser General Public License (LGPL)

  • Permissions: Similar to GPL but with more flexibility for linking, meaning LGPL code can be used in proprietary projects as long as changes to the LGPL code itself remain open-source.
  • Conditions: Derivative works based on the code itself must remain LGPL, but projects linking to it can be proprietary.
  • Limitations: Disclaims warranties.
  • Best For: Libraries intended for use in both open-source and proprietary projects.

Summary: Copyleft for libraries; allows proprietary use under specific conditions.

5. Creative Commons Zero (CC0)

  • Permissions: Effectively a “public domain” license; users can do anything with the code, including using it without credit.
  • Conditions: None required.
  • Limitations: Disclaims warranties.
  • Best For: When you want to give up all rights to the code and make it freely available for any use, no credit required.

Summary: Public domain dedication; useful for code you want to share with no restrictions.

Choosing the Right License

  • MIT or Apache 2.0: If you want maximum flexibility with fewer restrictions.
  • GPL 3.0: If you want to ensure derivative works remain open-source.
  • LGPL: If you’re releasing a library and want to allow linking in proprietary software.
  • CC0: If you want to relinquish all rights and let others use your code without restriction.

Each license has unique nuances, so consider your goals for your project and community when choosing.