In biology, mutualism is a relationship where each party benefits. The Mutualist License brings that idea to software: use it freely, but protect the people who make it and play fair with everyone else.

MutuaL is designed to be humane, equitable, clear, robust, sovereign without being isolationist, and modern. It is written in plain English as a flipped form, and it is a precise, serious legal tool for strong copyleft, not a "vibes license." If something does not make sense, that is MutuaL's fault, not yours: please open an issue so we can fix it.

Key features #

Plain language: Written in everyday English
Strong-as-it-needs-to-be copyleft: Copies you share, changed or not, and software based on MutuaL stay under MutuaL, so recipients get the same freedoms you did
Network-aware: Others who use a modified version over a network, or a service that depends on MutuaL for core functionality, must be offered its source
Cooperative: Combines with other free/open licenses without extending MutuaL's copyleft to parts kept in separate files
Patent-aware: Includes a patent grant and a clear "no patent attacks" rule. The rule binds only people who accepted the license.
Anti-DRM/anti-TiVoization: No technical measures that block users from exercising their rights
Contributor-friendly: Contributions remain part of the commons under the same license

Or, in choosealicense.com terms:

Permissions of this strong-as-it-needs-to-be copyleft license are conditioned on sharing MutuaL-licensed source, under the same license, with recipients and users of a network service that depends on it for core functionality, even if unchanged. License, copyright, and credit notices must be preserved, and no technical measures may stop recipients from exercising their rights. Contributors grant patent rights, and a patent attack on licensees forfeits all rights under the license. Copyleft does not reach other free or open source files combined with it.

We recommend reading the full license text to understand it completely. It is written to be readable for a reason.

Comparison with other licenses #

License	Copyleft Strength	Network Source	Patent Protection	Anti-DRM	Combines with other FOSS
MutuaL	Strongest¹	Yes	Yes	Yes	Yes
GPL-3.0	Strong	No	Yes	Yes	Limited
AGPL-3.0	Strongest	Yes	Yes	Yes	Limited
MPL-2.0	File-level	No	Yes	No	Yes

MutuaL sits between AGPL (strict copyleft) and MPL (file-level copyleft) in combining strong copyleft with cooperative licensing. Unlike GPL-family licenses, MutuaL is designed to coexist with other free/open licenses without extending its copyleft to components kept in separate files.

¹Scored for the core software. Code that only runs alongside MutuaL software, or talks to it through a documented standard interface, stays separate, and MutuaL does not extend its copyleft to it (see Clarity in the license). AGPL-3.0 is commonly read more broadly for plugins and linked code. That trade is deliberate.

SPDX® Identifier: MutuaL-1.3 (the default) or MutuaL-1.3-only. Pending OSI approval and SPDX inclusion; use the badge and file headers for now.

Contributing #

Contributions are welcome from developers, maintainers, lawyers, and anyone who cares about software freedom. The process is issue-first and deliberately slow, because a misplaced comma can change a clause. See CONTRIBUTING.md for the stress tests and the drafting rules, and file an issue to report unclear language or a potential conflict.

Versioning and "Foresight" #

This version or later (MutuaL-1.3, or the explicit MutuaL-1.3-or-later): Strongly recommended. A later version only takes effect if it is an official release and adds no restriction that would make you non-compliant.
Only this version (MutuaL-1.3-only): locks this exact version against upgrades.

The identifiers section covers how inseparable code under different versions combines, and the FAQ answers the rest.

Status and scope #

Version 1.3 is the latest release. Its text is published at the license's home, mutualist.dev, and it is the copy in this repository's LICENSE.md. main holds released versions, and devel carries work toward the next one. See Versions for every release and its status. MutuaL has not been formally reviewed by any standards organization. If you plan to use it in a high-stakes or commercial context, consult a qualified lawyer.

Nothing in this repository is legal advice.

Using MutuaL for your project #

The site's start page presents these blocks in order. They stay here because the page reads them from this repository at build time, so they cannot drift.

License summary #

Add this to your README:

## License

This project is licensed under the Mutualist License v1.3.  
Replace `1.3` with `1.3-only` to lock this exact version against upgrades.  
See the [LICENSE.md](LICENSE.md) file for the full text.

### Mutualist License summary

**Permissions**

- ✅ Commercial use
- ✅ Private / internal use
- ✅ Modification
- ✅ Distribution (source and binaries)
- ✅ Network / SaaS use
- ✅ Patent use (as described in the license)

**Conditions**

- ❗ Keep copyright, license, and credit notices (see "Credit" in the license)
- ❗ Offer its source when you distribute a version people install and run
- ❗ Share its source when others use your version over a network, or a service depends on it for core functionality
- ❗ License shared copies under MutuaL (same license)
- ❗ Don't add technical measures (like DRM) that stop users from exercising their rights
- ❗ Patent peace: a patent attack on another licensee ends all your rights under this license

**Limitations**

- ❌ No liability
- ❌ No warranty
- ❌ No trademark rights
- ❌ No implied endorsement

Badge #

MutuaL-1.3

Add this to your README:

![MutuaL-1.3](https://img.shields.io/badge/License-MutuaL--1.3-af2e1a?style=flat&labelColor=110402&link=https%3A%2F%2Fmutualist.dev)

For the -only variant, change MutuaL--1.3 to MutuaL--1.3--only:

![MutuaL-1.3-only](https://img.shields.io/badge/License-MutuaL--1.3--only-af2e1a?style=flat&labelColor=110402&link=https%3A%2F%2Fmutualist.dev)

File header example #

Use this in your source files (adapt to your language's comment conventions). Replace MutuaL-1.3 with MutuaL-1.3-only to lock this exact version.

// SPDX-License-Identifier: MutuaL-1.3
// Copyright © [year] [copyright holder(s)]
//
// Licensed under the Mutualist License v1.3. See LICENSE.md for the full
// text, or https://mutualist.dev.
//
// You must:
// - keep shared copies under this license
// - offer source when you distribute the software, or let others use it over a network
// - keep the copyright, license, and credit notices
// - add no technical measures that stop users from exercising their rights
//
// Provided "AS IS", without warranties of any kind.

The author #

The author of MutuaL, and current repository head, is Kat Suricata (Tangled).

License for this repository #

For the MutuaL license text:

Everyone is allowed to share copies of this license, as long as the text stays exactly as written, apart from the Credit block and the Short ID, which you complete. Changes to formatting, such as fonts, spacing, or layout, are fine. Clearly marked excerpts, quotations, and commentary are also fine. You may not change the terms of this license and still call it the Mutualist License. You are free to use this text as a starting point for your own license under a different name. If you do, credit back to us is appreciated, but not required.

The repository and surrounding text itself is licensed under CC BY-SA 4.0.

Clone this repository

The Mutualist License (MutuaL) #

Quick start #

What is MutuaL? #