Open Source License Guide

Everything you need to know about open source licenses

Permissive Licenses

Maximum freedom with minimal requirements. Perfect for commercial use.

MIT License

Low Risk

Simple and permissive with minimal conditions

Popularity
95%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Private use

⚠ Conditions

  • License and copyright notice

✗ Limitations

  • Liability
  • Warranty
Used by: React, jQuery, Node.js, Bootstrap
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Apache License 2.0

Low Risk

Permissive with patent protection

Popularity
85%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Patent use
  • Private use

⚠ Conditions

  • License and copyright notice
  • State changes

✗ Limitations

  • Liability
  • Trademark use
  • Warranty
Used by: Android, Apache, Kubernetes, TypeScript
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BSD 3-Clause

Low Risk

Similar to MIT with non-endorsement clause

Popularity
70%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Private use

⚠ Conditions

  • License and copyright notice

✗ Limitations

  • Liability
  • Warranty
Used by: Go, Django, Flask, NumPy
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ISC License

Low Risk

Simplified version of MIT/BSD licenses

Popularity
60%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Private use

⚠ Conditions

  • License and copyright notice

✗ Limitations

  • Liability
  • Warranty
Used by: npm packages, OpenBSD
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Weak Copyleft Licenses

Balance between freedom and protection. Library modifications must stay open.

LGPL v3.0

Medium Risk

GPL for libraries, allows proprietary linking

Popularity
65%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Patent use
  • Private use

⚠ Conditions

  • Disclose source
  • License and copyright notice
  • Same license (library)
  • State changes

✗ Limitations

  • Liability
  • Warranty
Used by: Qt, GTK, FFmpeg
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Mozilla Public License 2.0

Medium Risk

File-level copyleft, business-friendly

Popularity
55%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Patent use
  • Private use

⚠ Conditions

  • Disclose source
  • License and copyright notice
  • Same license (file)

✗ Limitations

  • Liability
  • Trademark use
  • Warranty
Used by: Firefox, Thunderbird, LibreOffice
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Eclipse Public License 2.0

Medium Risk

Weak copyleft with patent protection

Popularity
45%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Patent use
  • Private use

⚠ Conditions

  • Disclose source
  • License and copyright notice
  • Same license

✗ Limitations

  • Liability
  • Warranty
Used by: Eclipse IDE, JUnit, Jetty
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Strong Copyleft Licenses

Ensures software remains free. Derivatives must use the same license.

GPL v3.0

High Risk

Strong copyleft ensuring freedom

Popularity
75%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Patent use
  • Private use

⚠ Conditions

  • Disclose source
  • License and copyright notice
  • Same license
  • State changes

✗ Limitations

  • Liability
  • Warranty
Used by: Linux, GCC, GIMP, WordPress
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GPL v2.0

High Risk

Original strong copyleft license

Popularity
70%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Private use

⚠ Conditions

  • Disclose source
  • License and copyright notice
  • Same license
  • State changes

✗ Limitations

  • Liability
  • Warranty
Used by: Linux kernel, Git, MySQL
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AGPL v3.0

Very-high Risk

GPL for network services

Popularity
50%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Patent use
  • Private use

⚠ Conditions

  • Disclose source
  • License and copyright notice
  • Network use is distribution
  • Same license
  • State changes

✗ Limitations

  • Liability
  • Warranty
Used by: MongoDB, Nextcloud, Mastodon
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Public Domain Dedications

No restrictions. Use however you want.

CC0 1.0 Universal

Low Risk

Full public domain dedication

Popularity
40%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Private use

✗ Limitations

  • Liability
  • Patent use
  • Trademark use
  • Warranty
Used by: SQLite, Creative Commons assets
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The Unlicense

Low Risk

Simple public domain dedication

Popularity
35%

✓ Permissions

  • Commercial use
  • Distribution
  • Modification
  • Private use

✗ Limitations

  • Liability
  • Warranty
Used by: Various small libraries and tools
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Which License Should I Choose?

I want it simple and permissive

Anyone can do almost anything with your code

→ Choose MIT or Apache 2.0

I want to protect against patents

Explicitly grants patent rights to users

→ Choose Apache 2.0

I want improvements to be shared

Modifications must be open sourced

→ Choose GPL 3.0

I'm making a library

Allow proprietary software to use it

→ Choose LGPL 3.0 or MPL 2.0

I want a web service license

Network use counts as distribution

→ Choose AGPL 3.0

I don't care, public domain

No conditions whatsoever

→ Choose CC0 or Unlicense

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