Wikiversity
en.wikiversity.org
A Wikimedia project hosting free learning resources, courses, and research projects across all academic disciplines, editable by anyone.
Why it is useful
Provides structured learning pathways for academic topics that have no equivalent free course elsewhere — the breadth of subject coverage is unmatched because it relies on community contribution rather than professional course production. Particularly useful for niche academic topics where no Coursera or edX course exists. The research projects feature makes it an unusual open collaboration space.