Udemy

Udemy is the Wild West of online learning — 250,000+ courses from anyone willing to teach. Quality varies wildly, but the gems are extraordinary. The trick is buying during their perpetual sales (courses regularly drop from $200 to $10-15). Once purchased, you own the course forever. Their top instructors have millions of students. The platform works best for technical skills: Python, web development, data science, and cloud certifications. Over 75 million students have taken a Udemy course.