Choosing an open-source licence feels harder than it should be, because licence texts are long and the differences that matter are buried in them. This free matcher compares six common licences on four simple scores, permissiveness, copyleft, commercial use, and patent grants, ranked by whatever matters most to you.
What the tool does
You pick your top priority, maximum permissiveness, strong copyleft, commercial use, or patent protection, and the tool returns a comparison table of MIT, Apache-2.0, BSD-3-Clause, GPL-3.0, LGPL-3.0, and MPL-2.0, ranked by that priority, with scores from 1 to 5 on each dimension and a one-line note per licence. The ranking changes with your priority, which is the point: there is no single best licence, only a best fit for a project’s goals. The scores are a simplified aid, and the tool says so on the page.
How to use it
Choose the priority that matches your project’s real goal, not the one that sounds most impressive. A university releasing a tool for widest reuse usually wants permissiveness, while a project that must stay open in all derivatives wants copyleft. Press the button, read the top-ranked licences first, then read the notes for the top two before deciding. Check the full licence text of your chosen licence before applying it, and confirm that it is compatible with the licences of any code your project already includes.
Worked example
With maximum permissiveness as the priority, MIT and Apache-2.0 top the table, both scoring 5 for permissiveness and commercial use, while GPL-3.0 scores 3 for permissiveness and 5 for copyleft. Switch the priority to strong copyleft and GPL-3.0 moves to the top, with LGPL-3.0 second. The same six licences, two different answers, because the question changed. That is the correct behaviour: the matcher ranks by your goal, and a team that has not agreed its goal cannot pick a licence sensibly.
Reading the results honestly
Scores from 1 to 5 compress real legal differences into single numbers. Apache-2.0 and MIT look nearly identical on permissiveness, yet Apache-2.0 adds an express patent grant that MIT lacks, which can matter enormously for a project with patentable contributions. Copyleft scores hide similar detail: GPL-3.0 and LGPL-3.0 differ on linking, and MPL-2.0 applies copyleft at file level rather than project level. Use the table to shortlist two licences, then read those two texts in full before choosing.
Honest limits
This tool is a comparison aid, not legal advice. It covers six licences only, scores are simplified and arguable, and it does not consider your institution’s policies, funder requirements, contributor agreements, or the licences of dependencies. Some projects need dual licensing or a contributor licence agreement, neither of which this tool addresses. For important projects, especially commercial ones, ask a lawyer before applying a licence, and record the decision with the project.
Practical tips
Decide the licence before accepting outside contributions, since changing a licence later requires permission from every contributor. Put the licence file at the repository root and add a short header to source files, so the choice is unmistakable. If your institution or funder mandates a licence, that mandate overrides this matcher’s ranking, and the ranking is still useful for understanding what the mandated licence does and does not allow.
When dependencies conflict
The hardest licence problems come from dependencies: your code may be MIT, but a library it requires may be GPL, and the combination must satisfy both licences. Check the licences of every direct dependency before choosing your own, and remember that transitive dependencies count too, since a library’s library can impose terms you never saw. If a conflict appears, options include replacing the dependency, seeking a different licence for your code, or asking the dependency’s authors about an exception. Discovering the conflict before release is a minor inconvenience; discovering it after release, when users already rely on your code, is a genuine problem.
Related tools
Spanish version: Buscador de Licencias de Software de Código Abierto Gratis y Online · All free online tools.
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