Link: Coursera

Age Group: High School, College, & Adults

Description: Courses from universities and organizations in subjects such as arts, science, business, computer science, data science, health, and more

Strengths: Large Variety, User-Friendly Platform, & Verified Certificates

Weaknesses: Subscription Model & Limited Free Content

Link: edX

Age Group: High School, College, & Adults

Description: University-level courses in subjects including humanities, science, engineering, and social sciences

Strengths: High-Quality Courses & Partnerships with Top Universities

Weaknesses: Complicated User Interface

Link: MIT OpenCourseWare

Age Group: Advanced High School & College

Description: Provides lecture notes, exams, and videos from MIT courses in science, engineering, and more

Strengths: In-depth, university-level courses & a wide range of subjects

Weaknesses: Can be too advanced for younger students or those looking for basic overview

Link: Open Yale Courses

Age Group: College Students & Adults

Description: Selection of introductory courses taught by distinguished teachers and scholars at Yale University

Strengths: Variety & Depth

Weaknesses: No Accreditation