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Class Central

A Decade of Class Central: Over 50 Million Served

Class Central just turned 10! Here’s our recap of 2021, which saw Class Central expand into social learning.

Class Central homepage in December 2011
Class Central homepage in December 2011

What started out as a weekend side project ten years ago has now been used by over 50 million learners worldwide.

In October 2011, Stanford began to offer 3 of their courses online for free. This marked the birth of the modern MOOC movement. As more of these courses were being announced, over Thanksgiving weekend 2011, I built a one-page website to keep track of them.

Thus, Class Central was born, with a list of 16 online courses.

We're 10 – 50 Million Served

Class Central’s goal is to make online education work for everyone. The Class Central team primarily consists of learners from around the world. Since we take online courses ourselves, we know that building a catalog is just the first step.

Last year, I ended my review of Class Central with the following:

In 2020, we’ve been able to lay the groundwork and gain clarity on how to bring those ideas into reality in 2021 and beyond. 

The pandemic boost helped us take a step toward building an ecosystem of learning tools and services. In 2021, we continued to expand our catalog, we enabled on-platform learning via Classroom, and we launched Cohorts, a social layer for open courses.

Keep reading to find all about Class Central’s 2021.

By the Numbers

Class Central unique users per year
Class Central user growth and pandemic boost last year

2020 was Class Central’s biggest year: 40% of the people that have ever visited Class Central did so in 2020. This was due to the boost provided by the pandemic.

So we knew 2021 wasn’t going to be as big as 2020. But the pullback turned out to be bigger than we imagined because Class Central was impacted by changes to Google’s algorithm (or core updates) in July.

Class Central Cohorts

Cohorts Screenshot
Class Central Cohorts platform

Class Central Cohorts, a social learning platform for open courses, came out after more than a year of experimentation with social learning. It started with internal study groups, which expanded into public study groups, and eventually to an 8,000 learner bootcamp.

A Cohort has three main components:

  • An online course — that we’re all taking, following a common study schedule.
  • A discussion forum — where we discuss our learning and support each other.
  • Weekly Zoom sessions or live streams — where we chat with peers.

Learn more about Cohorts here.

Catalog Expansion

Class Central’s started out by aggregating MOOCs or free university online courses. But in 2021, we expanded our catalog beyond MOOCs. 

The Class Central catalog lists 50k online courses. This is thrice the number of courses we had in 2020. Besides providers like Coursera, edX, and FutureLearn, we also list courses from providers like Udemy, Skillshare, and LinkedIn Learning.

Class Central internal catalog dashboard

To achieve this expansion, we had to invest in improving our infrastructure. We built a classifier that maps courses to our handbuilt subject taxonomy.  

But automation is never perfect, and we rely on manual processes to ensure quality. An internal dashboard (shown above) helped us drastically improve the speed of these processes.

Finally, we redesigned our catalog pages to improve the user experience, adding new filters like “level” and “duration”.

Catalog Screenshot
Class Central new catalog design

Class Central Classroom

Classroom Screenshot
History of Science Cohort

At Class Central, we’re big fans of free and open education.

But as we started expanding our catalog to include paid offerings, we felt that we needed to provide reasonable free alternatives. For this, we turned to what is perhaps the world’s biggest online learning platform: YouTube.

We began curating YouTube playlists and encapsulated these playlists into a Classroom Experience: learners can now watch the videos on Class Central, and it automatically tracks and saves your progress.

Currently, we have curated around 3000 educational playlists.

Class Central Lists Update

Lists Screenshot
Class Central lists improved

After launching our Lists and Education Profile feature last summer, we revisited the project to add more powerful management tools.

The upgrade included an overhaul of the data structure and API that powers the backend, which allowed us to improve the user experience. Learners can now create lists with multi-level sections, descriptions, images, and documents.



Class Central users generally prefer browsing the catalog over using the search bar. Only 5% of them use search. This resulted in 800k searches.

Here are the top 25 search keywords:

harvard, python, english, marketing, psychology

law, excel, java, stock market, c

french, data science, writing, spanish, finance

machine learning, business, architecture, digital marketing, art,

Sql, music, korean, ingles, fashion 

Most Popular Courses

In 2021, courses on Class Central were bookmarked  1.4 million times. These are the 25 most-bookmarked courses. The top bookmarked course got 8.3K bookmarks, while #25 got 4.8K.

  1. English for the Workplace from British Council ★★★★★(1388)
  2. Computing in Python IV: Objects & Algorithms from Georgia Institute of Technology ★★★★★(78)
  3. Python for Everybody – Exploring Information
  4. Nutrition, Exercise and Sports from Wageningen University ★★★★★(980)
  5. Computing in Python II: Control Structures from Georgia Institute of Technology ★★★★★(49)
  6. Career planning: resume/CV, cover letter, interview from Tomsk State University ★★★★★(52)
  7. Computing in Python I: Fundamentals and Procedural Programming from Georgia Institute of Technology ★★★★★(199)
  8. Product Management Fundamentals from University System of Maryland ★★★★★(156)
  9. Presentation skills: Speechwriting and Storytelling from Tomsk State University ★★★★★(367)
  10. An Introduction to Interactive Programming in Python (Part 1) from Rice University ★★★★★(3310)
  11. Marketing in a Digital World from University of Illinois at Urbana-Champaign ★★★★★(169)
  12. Marketing Digital: Content & Community Manager from Galileo University ★★★★★(217)
  13. Presentation skills: Effective Presentation Delivery from Tomsk State University ★★★★★(128)
  14. Presentation skills: Designing Presentation Slides from Tomsk State University ★★★★★(812)
  15. Computing in Python III: Data Structures from Georgia Institute of Technology ★★★★★(40)
  16. HTML, CSS, and Javascript for Web Developers from Johns Hopkins University ★★★★★(22)
  17. Mindfulness for Wellbeing and Peak Performance from Monash University ★★★★★(210)
  18. Marketing Innovative Products and Services from University System of Maryland ★★★★★(47)
  19. Academic Writing Made Easy from Technische Universität München (Technical University of Munich) ★★★★★(39)
  20. Elements of AI from University of Helsinki ★★★★★(692)
  21. Psychology of Personal Growth from The Hong Kong University of Science and Technology ★★★★★(62)
  22. Six Sigma: Analyze, Improve, Control from Technische Universität München (Technical University of Munich) ★★★★★(670)
  23. Learning How To Learn for Youth from Arizona State University ★★★★★(780)
  24. Viruses & How to Beat Them: Cells, Immunity, Vaccines from Tel Aviv University ★★★★★(28)
  25. Improving Communication Skills from University of Pennsylvania ★★★★★(26)

Most Followed

Class Central’s Follow button enables learners to customize their experience by following universities, subjects, and course providers.

In 2021, our users followed 1.6 million items. Below are the 25 most followed items. The top item got 19K follows, while #25 got 12K.

  1. Communication Skills
  2. Language Learning
  3. Personal Development
  4. Self Improvement
  5. Grammar & Writing
  6. Management & Leadership
  7. Psychology
  8. Business
  9. Computer Science
  10. Leadership
  11. Design & Creativity
  12. Digital Marketing
  13. Programming
  14. Entrepreneurship
  15. Health & Medicine
  16. Mental Health
  17. Business Intelligence
  18. Project Management
  19. Social Media Marketing
  20. Programming Languages
  21. Marketing
  22. Microsoft Excel
  23. Data Analysis
  24. Web Design
  25. Online Education


In 2021, we saw the early steps of a Class Central learning ecosystem with Cohorts, Classroom, and Lists. In 2022, we want to flesh out this ecosystem further and make the different components of the ecosystem play better with each other.

Dhawal Shah Profile Image

Dhawal Shah

Dhawal is the CEO of Class Central, the most popular search engine and review site for online courses and MOOCs. He has completed over a dozen MOOCs and has written over 200 articles about the MOOC space, including contributions to TechCrunch, EdSurge, Quartz, and VentureBeat.

Comments 2

  1. Jim

    Wow, congrats to you and your team for reaching a milestone! The Reports are so in-depth that I always learn something from them. Of course, the most valuable content are the course reviews and curricular guides. Your expanding catalog will help learners discover which providers offer courses in specialized interests. Thank you for helping learners!

  2. Yuka

    Congrats on the 10th anniversary! I’ve been reading your reports since 2016.
    Thank you always for the information!


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