License Compatibility Checker
Check whether two software licenses can be combined.
Overview
Pick two open source licenses from a dropdown and the tool answers a single question: can a project that uses code under license A also include code under license B? The result is a yes/no with a one-line explanation - permissive merges with permissive, copyleft constrains permissive, and a few specific incompatibilities (GPLv2 vs Apache 2.0, GPL vs CDDL) are flagged.
It's for developers vendoring third-party code, building a redistributable product, or auditing transitive dependencies. Reach for it when adding a new dependency that's not under the same license as the rest of your stack, or when packaging a deliverable that downstream users will further redistribute.
How it works
The matrix encodes the well-known compatibility relationships among the most-used SPDX-identified licenses: MIT, Apache 2.0, BSD-2/3-Clause, ISC, MPL 2.0, LGPL 2.1/3.0, GPL 2.0/3.0, AGPL 3.0, and Unlicense. Compatibility is asymmetric - what you can include in a GPL project differs from what you can include in an MIT project.
The data follows the public guidance from the FSF, SPDX, and Apache Software Foundation Category-X lists. The tool is informational - it isn't legal advice, and edge cases involving "with classpath exception," "with linking exception," or commercial dual licensing need a real lawyer.
Examples
- MIT inside Apache 2.0 -> Yes (Apache is permissive and accepts more-permissive code).
- Apache 2.0 inside GPLv2 -> No (GPLv2 incompatible with Apache 2.0's patent clauses); GPLv3 is compatible.
- GPLv3 inside MIT-licensed app -> No (must release the combined work under GPLv3).
- Two BSD-3-Clause projects -> Yes (permissive + permissive).
FAQ
Is this legal advice?
No. License compatibility involves jurisdiction, distribution model, and use case - consult a lawyer for anything you're shipping commercially.
Why isn't GPLv2 compatible with Apache 2.0?
GPLv2 doesn't permit additional restrictions, and Apache 2.0's patent termination clause is treated as an additional restriction. GPLv3 explicitly added Apache 2.0 compatibility.
What about LGPL?
LGPL allows linking from a differently-licensed application (static linking with constraints, dynamic linking freely). The matrix flags the linking model so you can answer for your case.
Are commercial licenses covered?
The tool covers open source licenses. Commercial / proprietary licenses are bespoke - read the EULA and consult counsel for compatibility questions.