It’s been eight years since a few Stanford professors decided to offer their courses online for free. These courses are now commonly known as as MOOCs or Massive Open Online Courses.

And since then, over 900 universities have launched 13,500 online courses. These courses have been taken by 110 million learners.

Not all of these courses are free like they used to be. Some now charge for certifications or require you to pay to access the full course materials. But you can still audit them for free.

I’ve been keeping track of these courses the entire time over at Class Central - ever since free online courses rose to prominence. It's been 8 years since I founded Class Central, and have helped more than 20 million learners decide which online courses to take.

Methodology: How we determined the Top 100 Free Courses of 2019

First, we went through Class Central’s database and made a list of all the courses that were offered for the first time ever in 2019. We found that 450 universities around the world have now launched more than 2,500 courses.

Then Suparn wrote scrapers to collect enrollment numbers from three different course providers: Coursera, edX, and Swayam. Each of these providers show how many students are enrolled on their course pages. These three providers alone registered around 5 million enrollments for courses launched in 2019.

Along with this, we also explored data from our users. Most importantly, how many times a course has been bookmarked on Class Central.

Using the provider's enrollment data and our own bookmarks data, we came up with a list of 100 most popular courses of 2019 - a wide assortment from 68 universities.

You can also find this list on Class Central which I built using Class Central’s Custom List feature. Not all the courses on this list might be available, but if you bookmark a course on Class Central, we will let you know when it is offered next.

Here are the most popular free online university courses of 2019 (not ordered by popularity).