The Report by Class Central

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Course Report

The 100 Most Popular Online Courses of All Time (2021)

The best way to choose a free Massive Open Online Course (MOOC) is to choose one that other people have taken and enjoyed.


Most Popular of All Time

The best way to choose a free Massive Open Online Course (MOOC) is to choose one that other people have taken and enjoyed.

Class Central has been maintaining a catalog of these MOOCs ever since they rose to popularity back in 2012. According to Class Central’s 2019 annual report on MOOCs, 110M students have taken at least one course and over 900+ universities have launched 13,500 courses.

To help learners decide which course to take, Class Central publishes a number of different rankings based on the tens of thousands of reviews written by Class Central users.

In this ranking, we take a different approach. Instead of ranking courses by reviews, we rank by the number of students who enrolled in the course. In some cases, the top reviewed courses are also the courses with the most enrollments. In other cases, courses with large enrollments only have average reviews. This suggests there are popular courses that Class Central’s reviews have missed.

Interest in MOOCs and online education has never been greater. If you’re looking for a new online course, take a look at these free courses that millions of students have already taken.

  1. Machine Learning from Stanford University ★★★★★(361)
  2. The Science of Well-Being from Yale University ★★★★★(14)
  3. Learning How to Learn: Powerful mental tools to help you master tough subjects from University of California, San Diego ★★★★★(11897)
  4. CS50’s Introduction to Computer Science from Harvard University ★★★★★(90)
  5. Programming for Everybody (Getting Started with Python) from University of Michigan ★★★★★(13806)
  6. R Programming from Johns Hopkins University ★★★☆☆(243)
  7. Algorithms, Part I from Princeton University ★★★★★(60)
  8. The Data Scientist’s Toolbox from Johns Hopkins University ★★★☆☆(163)
  9. Introduction to Computer Science and Programming Using Python from Massachusetts Institute of Technology ★★★★☆(125)
  10. IELTS Academic Test Preparation from University of Queensland ★★★★★(4)
  11. Think Again I: How to Understand Arguments from Duke University ★★★★☆(8)
  12. Cryptography I from Stanford University ★★★★★(52)
  13. TOEFL® Test Preparation: The Insider’s Guide from ETS ★★★★★(3)
  14. Introduction to Philosophy from University of Edinburgh ★★★★☆(68)
  15. Analyzing and Visualizing Data with Excel from Microsoft ★★★★☆(13)
  16. Social Psychology from Wesleyan University ★★★★★(70)
  17. Developing Innovative Ideas for New Companies: The First Step in Entrepreneurship from University of Maryland, College Park ★★★★☆(34)
  18. Competitive Strategy from Ludwig-Maximilians-Universität München ★★★★★(22)
  19. Programming Mobile Applications for Android Handheld Systems: Part 1 from University of Maryland, College Park ★★★★☆(38)
  20. An Introduction to Interactive Programming in Python (Part 1) from Rice University ★★★★★(3207)
  21. Game Theory from Stanford University ★★★★☆(33)
  22. Successful Negotiation: Essential Strategies and Skills from University of Michigan ★★★★★(14)
  23. English for Career Development from University of Pennsylvania ★★★★☆(19)
  24. Model Thinking from University of Michigan ★★★★★(66)
  25. Chinese for Beginners from Peking University ★★★★☆(26)
  26. Introduction to Public Speaking from University of Washington ★★★★☆(9)
  27. Exploring English: Language and Culture from British Council ★★★★★(314)
  28. Understanding IELTS: Listening from British Council ★★★★★(278)
  29. English Grammar and Style from University of Queensland ★★★★☆(31)
  30. Introduction to Linux from Linux Foundation ★★★★☆(37)
  31. Neural Networks and Deep Learning from ★★★★★(15)
  32. Financial Markets from Yale University ★★★★☆(29)
  33. Inspiring Leadership through Emotional Intelligence from Case Western Reserve University ★★★★☆(23)
  34. Introduction to Artificial Intelligence from Stanford University ★★★★☆(25)
  35. Entrepreneurship in Emerging Economies from Harvard University ★★★★★(5)
  36. Introduction to Python for Data Science from Microsoft ★★★★☆(21)
  37. The Science of Happiness from University of California, Berkeley ★★★★★(32)
  38. Data Science: R Basics from Harvard University ★★★★★(10)
  39. Introduction to Python: Absolute Beginner from Microsoft ★★★☆☆(3)
  40. Grammar and Punctuation from University of California, Irvine ★★★★☆(30)
  41. Speak English Professionally: In Person, Online & On the Phone from Georgia Institute of Technology ★★★★☆(4)
  42. Buddhism and Modern Psychology from Princeton University ★★★★★(29)
  43. Analyzing and Visualizing Data with Power BI from Microsoft ★★★★★(3)
  44. Gamification from University of Pennsylvania ★★★★★(56)
  45. Bitcoin and Cryptocurrency Technologies from Princeton University ★★★★☆(19)
  46. English for the Workplace from British Council ★★★★★(508)
  47. Learn to Program: The Fundamentals from University of Toronto ★★★★★(105)
  48. First Step Korean from Yonsei University ★★★★☆(17)
  49. Introduction to Data Science in Python from University of Michigan ★★☆☆☆(44)
  50. Child Nutrition and Cooking from Stanford University ★★★★☆(29)
  51. Introduction to Financial Accounting from University of Pennsylvania ★★★★★(59)
  52. Introduction to Mathematical Thinking from Stanford University ★★★★☆(47)
  53. Contract Law: From Trust to Promise to Contract from Harvard University ★★★★☆(11)
  54. Stanford Introduction to Food and Health from Stanford University ★★★★☆(37)
  55. The Architectural Imagination from Harvard University ★★★★☆(10)
  56. Basic Spanish 1: Getting Started from Universitat Politècnica de València ★★★★☆(175)
  57. Introduction to Data Science from Microsoft ★★★★☆(6)
  58. Seeing Through Photographs from The Museum of Modern Art ★★★★☆(4)
  59. Justice from Harvard University ★★★★★(39)
  60. Mindfulness for Wellbeing and Peak Performance from Monash University ★★★★★(123)
  61. Introduction to Java Programming: Starting to code in Java from Universidad Carlos iii de Madrid ★★★★☆(6)
  62. HTML5 and CSS Fundamentals from World Wide Web Consortium (W3C) ★★★★☆(6)
  63. Financial Engineering and Risk Management Part I from Columbia University ★★★★☆(12)
  64. Greek and Roman Mythology from University of Pennsylvania ★★★★☆(18)
  65. AI For Everyone from ★★★★☆(4)
  66. Introduction to R for Data Science from Microsoft ★★★★☆(28)
  67. The Science of Everyday Thinking from University of Queensland ★★★★★(47)
  68. A Life of Happiness and Fulfillment from Indian School of Business ★★★★★(455)
  69. Fundamentals of Neuroscience, Part 1: The Electrical Properties of the Neuron from Harvard University ★★★★★(13)
  70. Finanzas personales from Universidad Nacional Autónoma de México
  71. Introduction to C++ from Microsoft ★★★★☆(7)
  72. Modern Art & Ideas from The Museum of Modern Art ★★★★★(5)
  73. Start Writing Fiction from The Open University ★★★★☆(20)
  74. Academic and Business Writing from University of California, Berkeley ★★★★☆(14)
  75. Marketing in a Digital World from University of Illinois at Urbana-Champaign ★★★★★(165)
  76. Gestión de Proyectos de Desarrollo from IDB (Inter-American Development Bank) ★★★★☆(2)
  77. 生活英语听说 | Conversational English Skills from Tsinghua University ★★★★☆(12)
  78. Introduction to Project Management from University of Adelaide ★★★★☆(6)
  79. Google Cloud Platform Fundamentals: Core Infrastructure from Google ★★★★☆(4)
  80. Fundamentals of Graphic Design from California Institute of the Arts ★★★★☆(18)
  81. How to Write an Essay from University of California, Berkeley ★★★★☆(26)
  82. A Beginner’s Guide to Writing in English for University Study from University of Reading ★★★★☆(22)
  83. Work Smarter, Not Harder: Time Management for Personal & Professional Productivity from University of California, Irvine ★★★★☆(40)
  84. PH525x: Data Analysis for Genomics from Harvard University ★★★★★(2)
  85. Statistics and R from Harvard University ★★★★☆(20)
  86. Mastering Data Analysis in Excel from Duke University ★★☆☆☆(25)
  87. Creativity, Innovation, and Change from Pennsylvania State University ★★★★☆(5)
  88. Introduction to Cyber Security from The Open University ★★★★☆(20)
  89. Primeros Auxilios Psicológicos (PAP) from Universitat Autònoma de Barcelona (Autonomous University of Barcelona) ★★★★★(1)
  90. Excel: Fundamentos y herramientas from Universitat Politècnica de València ★★★★★(267)
  91. Introductory Human Physiology from Duke University ★★★★☆(28)
  92. Technical Support Fundamentals from Google ★★☆☆☆(4)
  93. Python for Data Science from University of California, San Diego ★★★★☆(43)
  94. Artificial Intelligence (AI) from Columbia University ★★★★☆(11)
  95. Introduction to Programming with MATLAB from Vanderbilt University ★★★★★(201)
  96. Introduction to Psychology from University of Toronto ★★★★★(22)
  97. Understanding Language: Learning and Teaching from University of Southampton ★★★★☆(7)
  98. What is Data Science? from IBM ★★★☆☆(1)
  99. Project Management: The Basics for Success from University of California, Irvine ★★★★☆(25)
  100. Understanding Dementia from University of Tasmania ★★★★★(6742)
Christof Rindlisbacher Profile Image

Christof Rindlisbacher

Christof Rindlisbacher is a researcher and freelance journalist, currently focused on edtech.

Comments 8

  1. Avatar


    Thank you so much for sharing all the resources, really helpful and much appreciated.

  2. Avatar


    Thank you for sharing information. It is worth for teachers and students both. Even any person who is interested apart from his acedemic specialization can do it.

  3. Avatar

    Dr.Suvarna Sukhadeo Gund

    Thanks for new information . मराठी माषेसाठी असे कोसऀ आहेत का? नसतील तर आपण यासाठी काय करू शकता? यासाठी मराठी भाषिक म्हणुन मी या कोसऀसाठी प्रयत्न करु शकते.?
    Thanks .

  4. Avatar

    Muvaffak GÖZAYDIN

    What is the meaning of numbers next to name within paranthesis .

    • Suparn Patra

      Suparn Patra

      It is the number of reviews that course has received at Class Central.

  5. Avatar

    Lesa Taylor

    Good morning,
    I see that you are specializing in ed-tech. I am a ed-tech 11 in Maine. I am looking for free courses while i am home this summer. My job at a Boy Scout camp was closed due to COVID 19. Is there any courses for ed-tech to be able to get CEU’S?

    Thank you


  6. Avatar

    David Pérez Diego

    Hello, is there an approximate number of enrollments (historically) for each course? Or some sort of average per year/starting period?

    Thanks for the hard work, amazing data.

  7. Avatar

    Sally Mac

    Wow-this is great! T/you-Sally


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