====== Copyleft Licensing ======

===== Why License at All? =====

By default, everything you create is under exclusive copyright. Without a license, nobody can legally copy, distribute, or modify your work — even if it's publicly visible on GitHub. Choosing an open-source license is a declaration that you want your work to benefit everyone.

===== Free as in Freedom, Not Free Beer =====

"Free software" means free as in **libre** (freedom), not **gratis** (no cost). The four freedoms:

  - Run the program however you want
  - Study how it works
  - Redistribute it to help others
  - Improve it and share those improvements

===== Permissive vs. Copyleft =====

^ License ^ Type ^ Key Property ^
| MIT | Permissive | Anyone can use for anything; only attribution required |
| BSD | Permissive | Similar to MIT; multiple variants |
| Apache 2.0 | Permissive | Adds explicit patent grant |
| GPL v3 | Copyleft | Derivatives must use same license if distributed |
| **AGPL v3** | **Strong Copyleft** | Derivatives must use same license even if only run as a service |
| CC0 | Public Domain | All rights waived |

**The Sony/FreeBSD example:** Sony took FreeBSD 9.0 (permissive BSD license) and built the PlayStation 4's Orbis OS on top of it. Decades of community work absorbed into a proprietary commercial product with no obligation to give anything back. Permissive licenses allow this.

===== What Copyleft Does =====

Copyleft uses copyright law to ensure a work //remains// free. Instead of "all rights reserved," it's "these freedoms must be preserved."

If you modify copyleft-licensed work and distribute it, you **must** release your modifications under the same license. The code and its freedoms become legally inseparable — a "viral" effect that prevents enclosure.

===== AGPL v3 — The Network Loophole Fix =====

GPL requires sharing source code only when you **distribute** software. In the SaaS era, companies can modify GPL code, run it on their servers, and let users access it over the internet without ever distributing it — so they never have to share their changes.

[[https://www.gnu.org/licenses/agpl-3.0.en.html|AGPL v3]] closes this: if users interact with your software over a **network**, you must make the source available. Corporate SaaS users of AGPL code must contribute their modifications back.

**Recommendation:** Use AGPL v3 for software you want to remain free in the SaaS world.

===== Resources =====

  * [[https://choosealicense.com/|choosealicense.com]]
  * [[https://www.gnu.org/licenses/copyleft.en.html|GNU: What is Copyleft?]]
  * [[https://www.gnu.org/philosophy/free-sw.en.html|GNU: Free Software Definition]]

===== See Also =====
  * [[guides:start|Guides Index]]

  * [[guides:creative_commons|Creative Commons Licensing]]
  * [[folkzone:philosophy|Homelab Philosophy]]
  * [[indieweb:principles|IndieWeb Principles]]
  * [[start|Return to wiki home]]