Mozilla Public License 2.0 (MPL-2.0)

The Mozilla Public License 2.0 (MPL-2.0) is the "middle ground" of open source licenses. It is a weak copyleft license.

Can you use it commercially? Yes.
Can you modify it? Yes.
Must you share changes? Yes, but only for the files you modified.
Can you mix it with closed code? Yes, unlike the GPL, you can link MPL code with proprietary libraries without forcing the proprietary parts to become open source.

Factor	Risk Level	Notes
Vendor Lock-in	🟢 Low	Code is perpetually open.
Viral Effect	🟡 Medium	Only "viral" at the file level, not the project level.
Compliance Cost	🟡 Medium	You must track modified files.

File-Level Copyleft: If you modify file_a.c (MPL), you must share the source of file_a.c.
Compatibility: If you create file_b.c (Proprietary) and link it to file_a.c, file_b.c stays proprietary.
Notice: You must include the license text and copyright notice.