edX is a massive open online course (MOOC) provider. It hosts online university-level courses in a wide range of disciplines to a worldwide student body, including some courses at no charge. Developed by EdxOnline
License: Free
edX is focused on academic and professional courses from top universities, providing structured pathways and verified certificates, but at a higher cost. Udemy offers a wider range of affordable courses with lifetime access, though the quality can vary significantly.