Picking a license

What a license does

Without a license, the legal default is "all rights reserved," even for code posted publicly. You can look but can't reuse. The license is how you grant permission for others to use it. Every license on this page grants broad permissions, and every one of them is an open license. Only licenses which meet the OSI definition of Open Source are allowed on OSPREY at this time.

There is only one big decision to make: copyleft or permissive. After that it becomes a lot easier to pick out a license.

Copyleft: derivatives must stay open

Copyleft licenses let anyone use, modify, build on, and sell your work, with one condition: whoever publishes a derivative has to publish it under the same license. Nobody can take your work, improve it, and then close the improved version off. The commons only grows.

AGPL-3.0 (software) requires anyone who distributes a modified version, or runs one as a network service that others interact with, to publish their modifications under AGPL too.

CERN-OHL-S-2.0 (hardware) requires derivative designs to be released under the same license. It covers the design files, the firmware, and the documentation, so a hardware project needs no second license.

CC-BY-SA-4.0 (docs and data) is attribution plus share-alike. Adaptations have to carry the same license.

Permissive: anything goes, credit stays

Permissive licenses let anyone do nearly anything with your work, including building closed commercial products on top of it. The only obligation usually is keeping your copyright notice and the license text with any copy. Pick this side when the widest possible reuse matters more to you than keeping derivatives open.

MIT (software) is the shortest and most widely understood license in software. Derivatives have to keep the notice, otherwise they can do anything, and the author disclaims all warranty, so nobody can come after you when the pump firmware floods their lab. MIT says nothing about patents. If that matters to you, see Apache-2.0 below.

CERN-OHL-P-2.0 (hardware) is the hardware analog of MIT. Keep the notices, otherwise do anything, closed products included.

CC-BY-4.0 (docs and data) means reuse and adapt freely with credit. It's the standard for papers, figures, and documentation.

Other licenses

These sit under "Other licenses" in the dropdown, for the cases where one of them genuinely fits better.

Apache-2.0 (software, permissive) carries MIT's obligations plus a written patent promise. Every contributor agrees not to sue users for patent infringement over their contribution, and anyone who does sue automatically loses their license to the code. If your work sits near a patent portfolio, or your likely users are institutions that ask about patent language, pick Apache. Otherwise MIT is simpler.

GPL-3.0 (software, copyleft) is AGPL without the network clause, so sharing is triggered only by distribution. Some companies and institutions refuse AGPL code outright, and GPL-3.0 sometimes allowed where AGPL isn't. If your code will never plausibly run as a service, the two are equivalent in practice.

CERN-OHL-W-2.0 (hardware, weak copyleft) is the middle ground of the CERN hardware licenses. Changes to your design stay open, but the design can be a component inside a larger, possibly closed product. Typically published modules meant to be designed into bigger systems.

CC0-1.0 (data, public domain) is a dedication with no attribution required. It's right for datasets and metadata where requiring credit on every reuse would be impractical. For code, use MIT instead.

Need a license that isn't listed?

The list is deliberately short so picking stays easy, and it only carries licenses we've checked are genuinely open. If your work needs one that isn't here, ask through the Suggestion Box and we'll review it.