License Compatibility Checker

Apache-2.0 includes an explicit patent termination clause (section 3): if a contributor brings a patent claim, their licence is automatically revoked. The GPL-2.0 does not contain equivalent language, and its section 6 requires that no additional restrictions be placed on recipients beyond those stated in the GPL itself. The FSF considers Apache-2.0's patent clause an 'additional restriction', making the two licences legally incompatible for distribution in a single combined work.

Not directly, unless the GPL-2.0 code is licensed 'version 2 or later' (written as GPL-2.0+). Pure GPL-2.0 code and GPL-3.0 code are incompatible versions that cannot be merged into a single distributed binary. Many projects explicitly state 'GPL-2.0-or-later' in their headers to allow this upgrade path. Check the actual licence header of each library — the SPDX identifier GPL-2.0-only indicates no upgrade is permitted.

All three are copyleft licences from the FSF with increasing restriction. LGPL (Lesser GPL) allows linking from proprietary software without triggering copyleft — only modifications to the library itself must be shared. GPL (General Public License) requires any software that incorporates GPL code to also be distributed under the GPL when distributed publicly. AGPL (Affero GPL) extends this to network use: if you run AGPL software as a service (SaaS) and users interact with it over a network, you must publish the source — even without distributing a binary.

The Mozilla Public License 2.0 applies copyleft only at the file level, not the project level. If you modify an existing MPL-2.0 file, that file and its modifications must remain under MPL-2.0. However, new files you create — even in the same project — can be under any licence, including proprietary. This makes MPL-2.0 a 'weak' copyleft that allows mixing with proprietary code more freely than GPL, as long as MPL-licensed files are kept in separate files.

CC0-1.0 waives all copyright and related rights to the maximum extent permitted by law, placing the work as close to the public domain as legally possible. Since there are no restrictions on use, modification, or distribution, CC0 code can be incorporated into any project under any licence. Note: the FSF recommends against CC0 for software (preferring the Unlicense or MIT) because CC0 explicitly does not grant patent rights, whereas licences like MIT and Apache-2.0 do.