edX

edX is a learning platform founded by Harvard and MIT, where you'll find online courses from the world's most prestigious universities and companies. It's for anyone who wants to learn seriously and well, whether you're a complete beginner touching code for the first time or a professional topping up skills in data, business or artificial intelligence.

It works simply: you pick a course, register and start learning through video lectures, readings and hands-on exercises. Most courses can be taken for free in audit mode, where you get access to the learning materials. When you want a verified certificate with your name and graded assignments, you upgrade to the paid version.