Mozilla Public License 2.0
File-level copyleft. Modified files must be shared, but your other files can be proprietary.
Commercial use
✓ Yes
Modify
✓ Yes
Distribute
✓ Yes
Must open source changes
✗ No
Must attribute
✓ Yes
Patent grant
✓ Yes
What this license means
MPL 2.0 is a practical middle ground. If you modify an MPL-licensed file, you must share that specific file. But your own new files — even in the same project — can use any license, including proprietary. This file-level copyleft is much narrower than the GPL's project-level copyleft.
When you encounter this license
Good for libraries where you want to ensure improvements flow back to the community while still allowing commercial use. Firefox, LibreOffice, and Servo use MPL.
Watch out for
Compatible with GPL (you can combine MPL and GPL code). The file-level boundary is the key — don't modify the original MPL files if you want to keep things simple.
Tools using Mozilla Public License 2.0 (9)
Open source continuous file synchronization
Open source design and prototyping platform
Post-modern modal text editor
Open Terraform fork for declarative cloud infra
High-performance observability data pipeline
Simple and flexible tool for managing secrets
Fast lightweight search backend
Auth infrastructure for SaaS and AI apps
High-performance async messaging
This guide is for informational purposes only and does not constitute legal advice. For licensing decisions in commercial products, consult a qualified attorney.