Understanding Open Source Licenses
When choosing a design system, the license determines how you can use, modify, and distribute the code in your projects. This guide explains the most common licenses used by design systems.
MIT License
Type: Permissive
The MIT License is one of the most permissive and widely-used open source licenses. It allows you to do almost anything with the code as long as you include the original license and copyright notice.
What You Can Do
- Use the code commercially in proprietary products
- Modify the code however you want
- Distribute the original or modified code
- Sublicense (incorporate into projects with different licenses)
- Use privately without sharing modifications
Requirements
- Include the original MIT license and copyright notice in your code
Best For
Commercial projects, proprietary software, or when you want maximum flexibility without licensing concerns.
Design Systems Using MIT
MUI, Chakra UI, Mantine, shadcn/ui, Radix UI, Headless UI, Vuetify, DaisyUI, PrimeReact, Polaris, Ant Design, Fluent UI, Bootstrap, Primer, Forma 36, Sanity UI, Strapi Design System
Apache License 2.0
Type: Permissive (with patent protection)
Similar to MIT but includes explicit patent protection. If a contributor includes patented technology, they grant you rights to use those patents.
What You Can Do
- Use the code commercially
- Modify the code
- Distribute the original or modified code
- Sublicense under different terms
- Use privately
- Benefit from patent grant protection
Requirements
- Include the Apache License in your distribution
- State significant changes made to the code
- Include NOTICE file if one exists
- Preserve copyright, patent, and attribution notices
Best For
Enterprise projects where patent protection is important, or when working with corporate legal teams that prefer explicit patent grants.
Design Systems Using Apache 2.0
Material Design, Carbon Design System, Atlassian Design System
GNU General Public License 2.0 (GPL-2.0)
Type: Copyleft
GPL is a "copyleft" license, meaning if you distribute modified versions or software that includes GPL code, you must also release your source code under GPL.
What You Can Do
- Use the code commercially
- Modify the code
- Distribute the code
- Use privately (no distribution = no obligation to share source)
Requirements
- If you distribute: Must release your entire application's source code under GPL-2.0
- Include the GPL license with your code
- State changes made to the original code
- Disclose source code when distributing
- Include copyright and license notices
Important Considerations
Warning: GPL requires that any software you distribute that includes GPL code must also be GPL-licensed. This can be incompatible with proprietary or commercial software distribution.
Exception: If you only use the software internally without distributing it to others, you don't need to share your source code.
Best For
Open source projects, WordPress themes/plugins (WordPress ecosystem uses GPL), or projects committed to keeping all code open source.
Design Systems Using GPL-2.0
WordPress Components, Emulsify (Drupal)
For Commercial/Proprietary Software
If you're building proprietary software, carefully evaluate whether GPL is compatible with your business model. Consider MIT or Apache-licensed alternatives if you need to keep your code proprietary.
European Union Public License 1.2 (EUPL-1.2)
Type: Copyleft (with EU compatibility)
The EUPL is a copyleft license created by the European Commission. Similar to GPL, but designed specifically for EU institutions with explicit compatibility with other open source licenses.
What You Can Do
- Use the code commercially
- Modify the code
- Distribute the code
- Use privately (no distribution = no obligation to share source)
Requirements
- If you distribute: Must release source code under EUPL or compatible license
- Include the EUPL license with your code
- State changes made to the original code
- Disclose source code when distributing
- Include copyright and license notices
Key Differences from GPL
- Explicitly compatible with other copyleft licenses (GPL, OSL, etc.)
- Available in all 23 official EU languages
- Designed for cross-border use in EU member states
Best For
European Union projects, government institutions, or projects requiring explicit compatibility with multiple copyleft licenses.
Design Systems Using EUPL-1.2
OpenEuropa Theme (for EU institutional websites)
Quick Comparison
| Permission | MIT | Apache 2.0 | GPL-2.0 | EUPL-1.2 |
|---|---|---|---|---|
| Commercial use | ✓ | ✓ | ✓ | ✓ |
| Modification | ✓ | ✓ | ✓ | ✓ |
| Distribution | ✓ | ✓ | ✓ | ✓ |
| Private use | ✓ | ✓ | ✓ | ✓ |
| Patent protection | — | ✓ | — | ✓ |
| Proprietary use | ✓ | ✓ | ✗ (must disclose source) | ✗ (must disclose source) |
| Must disclose source | — | — | ✓ (when distributing) | ✓ (when distributing) |
| License compatibility | High | High | Limited | Explicit (GPL, OSL, etc.) |
Choosing the Right License
For maximum flexibility: Choose MIT-licensed design systems
For enterprise with patent concerns: Choose Apache 2.0-licensed systems
For open source projects: Any license works, but GPL ensures the ecosystem stays open
For WordPress projects: GPL is standard and compatible with WordPress licensing
Disclaimer
This guide provides general information about common open source licenses. It is not legal advice. For specific legal questions about licensing for your project, consult with a qualified attorney.