GNU General Public License 3.0

A copyleft license that ensures software remains free and open-source by requiring derivative works to adopt the same license, preserving users' freedoms to use, modify, and distribute the software.

License Text

                       GNU GENERAL PUBLIC LICENSE
                        Version 3, 29 June 2007

 Copyright (C) 2007 Free Software Foundation, Inc. 
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

                            Preamble

  The GNU General Public License is intended to guarantee your freedom 
  to share and change all versions of a program—to make sure it remains 
  free software for all its users. We, the Free Software Foundation, use 
  it for nearly all our software; you can apply it to your programs, too.

  When we speak of free software, we are referring to freedom, not price. 
  Our General Public Licenses are designed to make sure that you have 
  the freedom to distribute copies of free software

[The full license text continues with all standard GPL 3.0 terms including the requirement to retain copyright notices, distribution terms, source code availability, and copyleft provisions. This excerpt is abbreviated for brevity.]

View complete license text →

Key Features

Copyleft: Requires all derivative works and modifications to be distributed under the same license
Source Code Requirement: Must provide source code or an offer to provide it for any distributed binaries
Patent Protection: If you distribute GPL-covered software, you grant users a license to any patents covering it
Freedom Preservation: Guarantees users' rights to inspect, modify, and redistribute the software
Strong Reciprocity: Ensures that any improvements to the software remain freely available

When to Use This License

Choose the GPL 3.0 when:

You want to guarantee that all users have freedom to use, study, modify, and redistribute the software
Your project must remain free software regardless of how it's used or modified
You want to ensure modifications are shared back to the community
You need compatibility with the GNU ecosystem and other GPL-licensed projects

Copyleft Explained

Copyleft is a general method for making sure that programs are free. It requires that anyone who distributes a copylefted program must pass it on with the same freedom. GPL achieves this by requiring derivative works to adopt the same license, ensuring software freedom continues for all users. This stands in contrast to permissive licenses like MIT/Apache that allow use in proprietary software.

GPL Compliance

To comply with this license, you must:

Retain all copyright notices in distributed copies
Include a copy of the license with the software
Provide source code or offer to provide it
Allow modification and redistribution rights

GPL vs Other Licenses

✅ Preserves software freedom
⚠️ Not compatible with permissive licenses
❌ No explicit patent grants
🔄 Requires reciprocal licensing

License Summary

The GNU General Public License is the strongest free software license. By choosing GPL 3.0, you ensure that anyone who redistributes or modifies this program will pass along the same freedom to future users. It's particularly well-suited for projects where software freedom is a non-negotiable requirement.