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OSS licenses

A searchable summary of the common open-source licenses: what you can do, must do, and are not granted. Type to search by name or identifier, or filter by family. Everything runs in your browser.

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How it works

A searchable summary of the common open-source licenses, each broken down into what you can do, what you must do, and what the license does not provide. Choosing or obeying a license comes down to a few questions - can I use this commercially, do I have to publish my changes, is there a patent grant - and this lays the answers out side by side. Type to search by name or identifier, such as "MIT", "GPL", or "Apache", or use the chips to compare a whole family at once.

The licenses are grouped into permissive (do almost anything, just keep the notice), copyleft (share your changes under the same terms), and public-domain dedications (no conditions at all). Each card lists the permissions, conditions, and limitations using the same plain-language breakdown as choosealicense.com. This is a quick orientation, not legal advice. Everything is static and runs in your browser, so the lookup is instant and works offline.

Example. Searching "MIT" shows a permissive license: you may use, modify, and distribute it commercially, you must keep the copyright notice, and it comes with no warranty. Filtering by the Copyleft chip lines up the GPL family beside MPL and LGPL so you can see how far each one's "share your changes" requirement reaches.

FAQ

What is the difference between a permissive and a copyleft license?

A permissive license, such as MIT, BSD, or Apache, lets you do almost anything with the code - including building closed-source, commercial products on top of it - as long as you keep the original copyright and license notice. A copyleft license, such as the GPL, adds a reciprocity condition: if you distribute software that includes the code, you must release your version under the same license, keeping it open. Permissive licenses maximise adoption; copyleft licenses keep derivatives free.

What is the difference between the GPL, LGPL, and AGPL?

They are a family with increasing reach. The GPL is strong copyleft: a program that includes GPL code must itself be GPL. The LGPL weakens that for libraries, so you can link an LGPL library from proprietary software as long as changes to the library itself stay open. The AGPL strengthens it the other way: it closes the so-called "SaaS loophole" by treating use over a network as distribution, so if you run modified AGPL code as a web service you must offer users its source.

Why does the Apache 2.0 license mention patents?

Apache 2.0 includes an explicit patent grant: every contributor licenses any patents needed to use their contribution, and that grant terminates if you sue someone over the project for patent infringement. This protects users from a contributor later demanding patent royalties, a risk that older permissive licenses like MIT and BSD do not address in writing. It is one of the main reasons companies favour Apache 2.0 for larger projects. The GPLv3 added a comparable patent grant for the copyleft world.

What happens if a project has no license at all?

No license does not mean public domain - it means the opposite. By default, copyright law reserves all rights to the author, so without an explicit license nobody else has permission to use, copy, modify, or distribute the code, even if it is posted publicly. If you want others to use your work you must add a license, and if you want to dedicate it truly to the public domain, an explicit tool like the Unlicense or CC0 is the way to make that unambiguous.