EdX, founded in the heyday of the MOOC hype, is one of the world’s largest online course providers and boasts an active catalog of over 3,700 courses.

Some of the world’s most prestigious universities offer courses on edX: Harvard, MIT, Stanford, Oxford, and Cambridge. According to Class Central’s EdX’s 2021: Year in Review, edX has reached 42 million registered users.

Originally, edX was a nonprofit backed by MIT and Harvard. But in July 2021, it was acquired by 2U for $800 million dollars. To learn more about the acquisition, check out the in-depth article by @dhawal, the founder of Class Central: 2U + edX Analysis: Win for 2U, Risk for edX, Opportunity for Coursera.

The courses in the list below are free to audit — that is, you get access to the course materials for a limited time, but can’t access graded assignments and exams, and don’t receive a certificate of completion.

100 Top Free EdX Courses of All Time

The most popular edX course of all time is Harvard’s CS50 Introduction to Computer Science, which has over 4 million enrollments. Since its launch, CS50 has expanded into a brand that includes 11 courses. The whole series has received over 7.2 million enrollments.

Class Central’s @manoel has published a guide to help you select the right CS50 course for you.

Here’s a quick summary of edX’s 100 most popular free-to-audit online courses of all time, based on the number of enrollments:

• Enrollments range from 138K to 3.9M. There are five courses with over 1M enrollments.
• Together, they account for over 37M enrollments, with an average of 378K enrollments.
• Almost 30% of the courses are in the field of Data Science, Programming, and Machine Learning. The rest are distributed over a variety of domains.
• 95 courses are in English, and 5 are in Spanish.
• Combined, they represent thousands of hours of content.
• Around 75 courses are beginner level and 5 are advanced level.

Without further ado, here are the top 100 free edX courses available for free audit, sorted by number of enrollments:

1. CS50’s Introduction to Computer Science from Harvard University ★★★★★(143)
2. Introduction to Computer Science and Programming Using Python from Massachusetts Institute of Technology ★★★★☆(127)
3. IELTS Academic Test Preparation from University of Queensland ★★★★★(5)
4. TOEFL® Test Preparation: The Insider’s Guide from ETS ★★★★★(6)
5. CS50’s Web Programming with Python and JavaScript from Harvard University ★★★★★(20)
6. Analyzing and Visualizing Data with Excel from Microsoft ★★★★☆(14)
7. Introduction to Linux from Linux Foundation ★★★★☆(37)
8. Data Science: R Basics from Harvard University ★★★★★(11)
9. English Grammar and Style from University of Queensland ★★★★☆(34)
10. Entrepreneurship in Emerging Economies from Harvard University ★★★★★(10)
11. Introduction to Data Analysis using Excel from Microsoft ★★★★☆(7)
12. Python Basics for Data Science from IBM ★★☆☆☆(3)
13. Rhetoric: The Art of Persuasive Writing and Public Speaking from Harvard University ★★★★☆(3)
14. The Science of Happiness from University of California, Berkeley ★★★★★(33)
15. CS50’s Introduction to Artificial Intelligence with Python from Harvard University ★★★★★(10)
16. CS50’s Introduction to Game Development from Harvard University ★★★★☆(4)
17. Basic Spanish 1: Getting Started from Universitat Politècnica de València ★★★★☆(386)
18. Programming for Everybody (Getting Started with Python) from University of Michigan ★★★★★(1)
19. Contract Law: From Trust to Promise to Contract from Harvard University ★★★★★(13)
20. Justice from Harvard University ★★★★★(50)
21. The Architectural Imagination from Harvard University ★★★★☆(12)
22. Fundamentals of Neuroscience, Part 1: The Electrical Properties of the Neuron from Harvard University ★★★★★(20)
23. Introduction to Project Management from University of Adelaide ★★★★☆(6)
24. Data Science: Machine Learning from Harvard University ★★★★☆(3)
25. Excel: Fundamentos y herramientas from Universitat Politècnica de València ★★★★★(548)
26. HTML5 and CSS Fundamentals from World Wide Web Consortium (W3C) ★★★★☆(6)
27. Academic and Business Writing from University of California, Berkeley ★★★★☆(17)
28. Statistics and R from Harvard University ★★★★☆(20)
29. How to Write an Essay from University of California, Berkeley ★★★★☆(26)
30. Introduction to Java Programming: Starting to code in Java from Universidad Carlos iii de Madrid ★★★★☆(7)
31. Mechanical Ventilation for COVID-19 from Harvard University ★★★★★(24)
32. Gestión de proyectos de desarrollo from IDB ( Inter-American Development Bank ) ★★★★☆(2)
33. Conversational English Skills | 生活英语听说 from Tsinghua University ★★★★☆(12)
34. Principles of Biochemistry from Harvard University ★★★★★(12)
35. The Science of Everyday Thinking from University of Queensland ★★★★★(47)
36. Exercising Leadership: Foundational Principles from Harvard University ★★★★★(1)
37. Introduction to C++ from Microsoft ★★★★☆(7)
38. CS50’s Mobile App Development with React Native from Harvard University ★★★★☆(1)
39. Using Python for Research from Harvard University ★★★★☆(12)
40. Python for Data Science from University of California, San Diego ★★★★☆(47)
41. Leaders of Learning from Harvard University ★★★★☆(19)
42. Italian Language and Culture: Beginner (2021-2022) from Wellesley College ★★★★☆(3)
43. Introduction to Java Programming – Part 1 from The Hong Kong University of Science and Technology ★★★☆☆(6)
44. Probability – The Science of Uncertainty and Data from Massachusetts Institute of Technology ★★★★★(34)
45. Supply Chain Fundamentals from Massachusetts Institute of Technology ★★★★★(14)
46. Introduction to Kubernetes from Linux Foundation
47. Child Protection: Children’s Rights in Theory and Practice from Harvard University ★★★★★(5)
48. HTML5 Coding Essentials and Best Practices from World Wide Web Consortium (W3C) ★★★★☆(11)
49. Supply Chain Analytics from Massachusetts Institute of Technology ★★★☆☆(3)
50. A Hands-on Introduction to Engineering Simulations from Cornell University ★★★★★(2)
51. Programming Basics from Indian Institute of Technology Bombay ★★★☆☆(18)
52. CS50’s Introduction to Programming with Python from Harvard University ★★★★★(1)
53. Inglés básico: conversacional y networking from Universidad Anáhuac ★★★★★(51)
54. Learn to Program in Java from Microsoft ★★★★★(5)
55. Querying Data with Transact-SQL from Microsoft ★★★★☆(4)
56. Data Science: Visualization from Harvard University ★★★★★(3)
57. Becoming a Successful Leader (Inclusive Leadership Training)
58. Nutrition and Health: Macronutrients and Overnutrition from Wageningen University ★★★★★(307)
59. Computing in Python I: Fundamentals and Procedural Programming from Georgia Institute of Technology ★★★★★(222)
60. How to Learn Online
61. Statistical Thinking for Data Science and Analytics from Columbia University ★★☆☆☆(19)
62. Introduction to Computational Thinking and Data Science from Massachusetts Institute of Technology ★★★★☆(31)
63. Introduction to Marketing from The University of British Columbia ★★★★★(6)
64. Buddhism Through Its Scriptures from Harvard University ★★★★☆(6)
65. JavaScript Introduction from World Wide Web Consortium (W3C) ★☆☆☆☆(1)
66. Cybersecurity Fundamentals from Rochester Institute of Technology ★★★★★(25)
67. Introduction to Biology – The Secret of Life from Massachusetts Institute of Technology ★★★★★(124)
68. Bitcoin and Cryptocurrencies from University of California, Berkeley
69. Human Anatomy: Musculoskeletal Cases from Harvard University ★★★★★(8)
70. Science & Cooking: From Haute Cuisine to Soft Matter Science (chemistry) from Harvard University ★★★★★(14)
71. Data Science: Probability from Harvard University ★★★★☆(2)
72. Marketing Digital: Content & Community Manager from Galileo University ★★★★★(227)
73. Machine Learning with Python: from Linear Models to Deep Learning from Massachusetts Institute of Technology ★★★☆☆(25)
74. Becoming an Entrepreneur from Massachusetts Institute of Technology ★★★★★(5)
75. The Health Effects of Climate Change from Harvard University ★★★★★(6)
76. The Psychology of Criminal Justice from University of Queensland ★★★★★(16)
77. Operations Management from Indian Institute of Management Bangalore ★★★★☆(2)
78. Pyramids of Giza: Ancient Egyptian Art and Archaeology from Harvard University ★★★★★(5)
79. Machine Learning for Data Science and Analytics from Columbia University ★★★☆☆(15)
80. C Programming: Getting Started from Dartmouth College
81. Hinduism Through Its Scriptures from Harvard University ★★★★☆(3)
82. Improving Global Health: Focusing on Quality and Safety from Harvard University ★★★★☆(10)
83. Introduction to Algebra from Schoolyourself ★★★★★(19)
84. CS50’s Computer Science for Lawyers from Harvard University ★★★★★(4)
85. Programación para todos (empezando con Python) from University of Michigan ★★★★☆(1)
86. Introduction to Hyperledger Blockchain Technologies from Linux Foundation ★★★★☆(1)
87. Excel: gestión de datos from Universitat Politècnica de València ★★★★★(49)
88. Introduction to Corporate Finance from Columbia University ★☆☆☆☆(1)
89. Christianity Through Its Scriptures from Harvard University ★★★★☆(7)
90. Creative Problem Solving and Decision Making from Delft University of Technology ★★☆☆☆(4)
91. Introduction to Probability from Harvard University ★★★★★(1)
92. Introduction to Family Engagement in Education from Harvard University ★★★★★(8)
93. Solar Energy from Delft University of Technology ★★★★★(8)
94. People Management from Indian Institute of Management Bangalore
95. How to Code: Simple Data from The University of British Columbia ★★★★☆(15)
96. Humanitarian Response to Conflict and Disaster from Harvard University ★★★★★(8)
97. The Analytics Edge from Massachusetts Institute of Technology ★★★★★(80)
98. Drawing Nature, Science and Culture: Natural History Illustration 101 from University of Newcastle ★★★★★(2)
99. PredictionX: Omens, Oracles & Prophecies from Harvard University ★★★☆☆(2)
100. Fundamentals of Statistics from Massachusetts Institute of Technology ★★★★☆(10)