It’s been ten years since a few Stanford professors decided to offer their courses online for free. These later became known as MOOCs, for Massive Open Online Courses, and 2012 became the ‘Year of the MOOC’.

Over the years, the online course offering has continued to grow, to the point that it can be hard to navigate at time. So in this article, I’ve leveraged Class Central’s database of over 50,000 courses as well as course enrollment numbers to build a list of the 100 most popular online courses of the year.

If these courses don’t interest you, either browse Class Central’s extensive catalog of 50,000 online courses via our subjects page, or have a look at our curated course collections:

Methodology

First, I went through Class Central’s database and made a list of all the courses that were offered for the first time ever in 2021. This was around 2900 courses.

Then I wrote scrapers to collect enrollment numbers across four different providers: Coursera, edX, FutureLearn, and Swayam. They all show how many students are enrolled on their course pages.

Combined, these providers have garnered over 6.8 million enrollments for courses launched in 2021. The 100 most popular courses account for over half of these enrollments.

Most Popular Free Online Courses

One fifth all the courses in the most popular list came from Google. The most popular course has over half a million enrollments.

Two courses from popular MOOC instructor Barbara Oakley also made the list. These courses, Uncommon Sense Teaching and Learn Like a Pro, are also part of Class Central’s Best of All Time compilation.

Below are the most popular free online courses launched in 2021 (sorted by number of enrollments).

Foundations: Data, Data, Everywhere
Google via Coursera
In this course, you’ll be introduced to the world of data analytics through hands-on curriculum developed by Google.
★★★★★ (1 rating)

Foundations of Project Management
Google via Coursera
This course is the first in a series of six to equip you with the skills you need to apply to introductory-level roles in project management.

Foundations of User Experience (UX) Design
Google via Coursera
Foundations of User Experience (UX) Design is the first of a series of seven courses that will equip you with the skills needed to apply to entry-level jobs in user experience design.

Ask Questions to Make Data-Driven Decisions
Google via Coursera
The material will help you learn how to ask effective questions to make data-driven decisions, while connecting with stakeholders’ needs.

Prepare Data for Exploration
Google via Coursera
You’ll learn how to use tools like spreadsheets and SQL to extract and make use of the right data for your objectives and how to organize and protect your data.

Project Initiation: Starting a Successful Project
Google via Coursera
This course will show you how to set a project up for success in the first phase of the project life cycle: the project initiation phase.

Process Data from Dirty to Clean
Google via Coursera
In this course, you’ll continue to build your understanding of data analytics and the concepts and tools that data analysts use in their work.

Start the UX Design Process: Empathize, Define, and Ideate
Google via Coursera
In this course, you’ll complete the first phases of the design process for a project that you’ll be able to include in your portfolio.

Psychological First Aid: Supporting Children and Young People
Public Health England via FutureLearn
Get Psychological First Aid training to support children and young people’s mental health during emergencies and crisis situations

Analyze Data to Answer Questions
Google via Coursera
In this course, you’ll explore the “analyze” phase of the data analysis process. You’ll take what you’ve learned to this point and apply it to your analysis to make sense of the data you’ve collected.

Excel for Everyone: Core Foundations
The University of British Columbia via edX
Learn Excel fundamentals including data wrangling, spreadsheet management, and basic data analysis.

Data Analysis with R Programming
Google via Coursera
You’ll discover how R lets you clean, organize, analyze, visualize, and report data in new and more powerful ways.

Introduction to Statistics
Stanford University via Coursera
You will gain the foundational skills that prepare you to pursue more advanced topics in statistical thinking and machine learning.
★★★★★ (1 rating)

Share Data Through the Art of Visualization
Google via Coursera
This course will show you how data visualizations, such as visual dashboards, can help bring your data to life. You’ll also explore Tableau, a data visualization platform that will help you create effective visualizations for your presentations.

Agile Project Management
Google via Coursera
This course will explore the history, approach, and philosophy of Agile project management, including the Scrum framework.
★★★★★ (1 rating)

Project Planning: Putting It All Together
Google via Coursera
This course will explore how to map out a project in the second phase of the project life cycle: the project planning phase.

Google Data Analytics Capstone: Complete a Case Study
Google via Coursera
This course is the eighth course in the Google Data Analytics Certificate. You’ll have the opportunity to complete an optional case study, which will help prepare you for the data analytics job hunt.

Nature-based Solutions for Disaster and Climate Resilience
SDG Academy via edX
What are ‘Nature-based solutions’, or NbS? How can they help build resilience to disasters and climate change impacts? Why is NbS relevant? How can I apply NbS in my work and everyday life?

Build Wireframes and Low-Fidelity Prototypes
Google via Coursera
In this course, you’ll continue to design a mobile app for your professional UX portfolio.

AWS Cloud Technical Essentials
Amazon Web Services via Coursera
Are you in a technical role and want to learn the fundamentals of AWS? Do you aspire to have a job or career as a cloud developer, architect, or in an operations role? If so, AWS Cloud Technical Essentials is an ideal way to start.

Project Execution: Running the Project
Google via Coursera
This course will delve into the execution and closing phases of the project life cycle. You will learn what aspects of a project to track and how to track them.

Python Project for Data Science
IBM via Coursera
This mini-course is intended to for you to demonstrate foundational Python skills for working with data. The completion of this course involves working on a hands-on project where you will develop a simple dashboard using Python.

Basic course in Biomedical Research- Cycle 5
National Institute of Epidemiology via Swayam
The course will explain the fundamental concepts of research methodology in health. Course materials include video lectures reading/resource materials, example accompaniments, workbooks, lecture handouts and frequently asked questions (based on participant queries from previous cycle).

Conduct UX Research and Test Early Concepts
Google via Coursera
In this course, you will learn how to plan and conduct a usability study to gather feedback about designs.

Learn English Through TV Drama Series: Skipper’s Pass
Chasing Time English via FutureLearn
Improve your English language skills by watching a short television drama series.

AWS Cloud Practitioner Essentials
Amazon Web Services via Coursera
This course will provide you with an understand of fundamental AWS Cloud concepts to help you gain confidence to contribute to your organization’s cloud initiatives.

Introduction to Google Workspace Administration
Google Cloud via Coursera
You will be introduced to your Cloud Directory and will learn how to split your organization into organizational units to simplify user and service management.

Introduction to Machine Learning in Production
deeplearning.ai via Coursera
In the first course of Machine Learning Engineering for Production Specialization, you will identify the various components and design an ML production system end-to-end: project scoping, data needs, modeling strategies, and deployment constraints and requirements; and learn how to establish a model baseline, address concept drift, and prototype the process for developing, deploying, and continuously improving a productionized ML application.

Create High-Fidelity Designs and Prototypes in Figma
Google via Coursera
In this course, you will follow step-by-step tutorials to learn how to create high-fidelity designs, called mockups, in Figma, a popular design tool.

Capstone: Applying Project Management in the Real World
Google via Coursera
In this final, capstone course of the Google Project Management Certificate, you will practice applying the project management knowledge and skills you have learned so far.

Inglés para todos: nivel básico
Universidad del Rosario via edX
Este curso te proporciona herramientas para que inicies tu aprendizaje de inglés desde las expresiones y estructuras más básicas.

The Digital Marketing Revolution
University of Illinois at Urbana-Champaign via Coursera
This course examines this issue by asking how the Digital Revolution has impacted marketing in an analog world. The learning approach will be highly interactive, meaning that you will have both the opportunity to engage in a variety of hands-on activities and to participate as a member of a rich learning community.

CS50’s Introduction to Programming with Scratch
Harvard University via edX
A gentle introduction to programming that prepares you for subsequent courses in coding.

Financial Accounting
Massachusetts Institute of Technology via edX
How do investors, creditors, and other users analyze financial statements to assess corporate performance? Learn financial accounting, how to read financial statements, and how to gather inputs to valuation models.

Responsive Web Design in Adobe XD
Google via Coursera
In this course, you will design a responsive website using Adobe XD, a popular design tool. You will complete the design process from beginning to end: empathizing with users, defining their pain points, coming up with ideas for design solutions, creating wireframes and prototypes, and testing designs to get feedback.

Early Childhood Development: Global Strategies for Implementation
Harvard University via edX
Examine best practices in child and family policies, advocacy, financing, and pathways to scale—learning how to generate innovative, scalable intervention strategies that supports early childhood development.

Mathematical Methods for Quantitative Finance
Massachusetts Institute of Technology via edX
Learn the mathematical foundations essential for financial engineering and quantitative finance: linear algebra, optimization, probability, stochastic processes, statistics, and applied computational techniques in R.

Mental Health and Nutrition
University of Canterbury via edX
Learn what foods and nutrients should and should not be consumed to improve mental wellbeing and explore the fundamental role that nutrition plays in our mental health.

Basics of Remote sensing, GIS & GNSS technology and their applications
Indian Institute of Remote Sensing via Swayam
During the course, the participants will be exposed to Basic Principles of Remote Sensing, Earth Observation Sensors and Platforms, Thermal Remote Sensing, Spectral Signatures of Different Land cover Features and Visual Image interpretation and Hyperspectral Remote Sensing technology.

A Bridge to the World: Korean Language for Beginners Ⅰ
Sungkyunkwan University via Coursera
This course is an introductory course to Korean language that aims to cultivate basic communication skill for those that are interested in learning Korean language.

Remote Work Revolution for Everyone
Harvard Business School via edX
You will learn to excel in the virtual-work landscape. You will learn how to build trust, increase productivity, use digital tools intelligently, and remain fully aligned with your remote team.

Food Fermentation: The Science of Cooking with Microbes
Harvard University via edX
Explore the roles that microbes play in the production, preservation, and enhancement of diverse foods in a variety of culinary traditions, and learn about the history of food fermentations.

Introduction to Microsoft Azure Cloud Services
Microsoft via Coursera
This course provides you with everything you need to get started. It introduces you to Microsoft Azure core concepts and services. You’ll learn the basics of cloud computing, its advantages, and how to choose the right Microsoft Azure solution for different business scenarios.

Design a User Experience for Social Good & Prepare for Jobs
Google via Coursera
In this course, you will design a dedicated mobile app and a responsive website focused on social good.

Data for Better Lives: A New Social Contract
Open Learning Campus – World Bank Group via edX
With this course, explore the 2021 World Development Report (WDR) and how data can be used for advancing development outcomes. Learn about the principles of a new social contract for data and data governance needed to transform lives for the poor.

Introduction to Data Engineering
IBM via Coursera
This course introduces you to the core concepts, processes, and tools you need to know in order to get a foundational knowledge of data engineering.

Fundamentals of Digital Marketing
University System of Maryland via edX
Learn the varied and changing approaches to digital marketing, such as mobile and omnichannel marketing and attribution and marketing mix modeling to inform your organization’s digital marketing strategy.

Human Resources Analytics
University of California, Irvine via Coursera
This course focuses on identifying effective data sources, developing meaningful metrics, designing long-term measures, and applying results in support of organizational strategy and tactics.

Entrepreneurship Adventures – مغامرات ريادة الأعمال
King Abdullah University of Science and Technology (KAUST) via edX
ستخوض في كل أسبوع مغامرة شيقة لتتحدى أفكارك المسبقة عن ريادة الأعمال وتختبر قدراتك القيادية وتتعلم من مغامرات أصحاب المشاريع الريادية. بنهاية هذه المغامرة سجد فرصتك لبداية مشروعك الريادي!

Bookkeeping Basics
Intuit via Coursera
In this course, you will be introduced to the role of a bookkeeper and learn what bookkeeping professionals do every day.

Deploying TinyML
Harvard University via edX
Learn to program in TensorFlow Lite for microcontrollers so that you can write the code, and deploy your model to your very own tiny microcontroller. Before you know it, you’ll be implementing an entire TinyML application.

Learn Like a Pro: Science-Based Tools to Become Better at Anything
via edX
Do you spend too much time learning, with disappointing results? Do you put off studying because it’s boring and you’re easily distracted? This course is for you!
★★★★★ (89 ratings)

Database Design and Basic SQL in PostgreSQL
University of Michigan via Coursera
In this course you will learn more about the historical design of databases and the use of SQL in the PostgreSQL environment.

Introduction to Node.js
Linux Foundation via edX
Get started with Node.js, the most popular open source JavaScript runtime. Discover the ways in which Node.js helps in everyday computing scenarios, from service-mocking, rapid-prototyping and real-time applications, to Command Line Interfaces (CLI).
★★☆☆☆ (1 rating)

Excel Skills to Make an Impression
Excel Club via FutureLearn
Learn intermediate and advanced Excel skills, such as pivot tables, IF statements, and dynamic arrays, to advance your career.

Game Design and Development 1: 2D Shooter
Michigan State University via Coursera
If you love games and want to learn how to make them, then this course will start you down that path.

Methods of molecular biology
St. Petersburg State Polytechnic University via Coursera
This multidisciplinary course will be interesting for students and specialists in the field of chemistry, ecology, mathematics, physics, medicine, and legal sciences, as well as to a wider audience, since it reveals various aspects of molecular biology and its methodological tools in an interesting and comprehensive language.

Scripting with Python
Southern New Hampshire University via edX
Explore fundamental programming with hands-on activities that help you build applications using Python.

Excel for Everyone: Data Analysis Fundamentals
The University of British Columbia via edX
Perform advanced data wrangling, analysis and dashboard visualization to help drive strategic decision-making.

Exploring Body Neutrality and Body Image with Jameela Jamil
Tommy Hilfiger via FutureLearn
Reclaim power over your own self-worth and learn from Jameela Jamil how you can transform your body image and practice self-love.

Data Structures & Algorithms I: ArrayLists, LinkedLists, Stacks and Queues
Georgia Institute of Technology via edX
Work with the principles of data storage in Arrays, ArrayLists & LinkedList nodes. Understand their operations and performance with visualizations. Implement low-level linear, linked data structures with recursive methods, and explore their edge cases. Extend these structures to the Abstract Data Types, Stacks, Queues and Deques.

Uncommon Sense Teaching
via Coursera
You’ll discover why you should help students use two different neural routes to help them be both flexible and fast in their learning.
★★★★★ (149 ratings)

Google Workspace Mail Management
Google Cloud via Coursera
In this course you will learn how to protect your organization against spam, spoofing, phishing and malware attacks.

Get Started With Digital Marketing
Coventry University via FutureLearn
What is digital marketing and why is it so valuable to businesses in today’s world? Find out with Coventry University Online.

CAD/CAM Computer Aided Design / Computer Aided Manufacturing
IGNOU via Swayam
The Computer Aided design (CAD) is a Process use of Computers and software’s to aid in the creation, Modification, Analysis, or Optimization of a design.

Building your Screenplay
University of Cambridge via edX
This course will broaden your understanding of how to start a career successfully as a professional screenwriter, as well as offer you insights in how to maximise and enjoy the processes of your personal creativity.

IELTS Listening and Speaking Sections Skills Mastery
University of California, Irvine via Coursera
The lessons in this course will improve your overall skills in both listening and speaking, and they will prepare you for every type of question in these sections of the test, increasing your chances of getting your target band scores.

Academic Writing in English for ESL Learners
University College London via FutureLearn
Develop your academic writing skills in English as a second language (ESL) learner and advance your English writing at university.

Operations Research (1): Models and Applications
National Taiwan University via Coursera
This course introduces frameworks and ideas about various types of optimization problems in the business world. In particular, we focus on how to formulate real business problems into mathematical models that can be solved by computers.

Programación en Python
Universidad de los Andes via Coursera
¡Te damos la bienvenida al curso de Programación en Python de la Universidad de los Andes!

С/C++ for competitive programming
Moscow Institute of Physics and Technology via Coursera
The “C/C++ for competitive programming” online course will introduce the basic concepts of the language, such as variables, data types.

Penetration Testing – Discovering Vulnerabilities
New York University (NYU) via edX
Learn fundamentals of penetration testing, including an Introduction to Penetration Testing Methodologies, Recognisance and Enumeration for Penetration Testers, Scanning and Vulnerability Enumeration.

Digital Marketing Analytics: Tools and Techniques
University of Maryland, College Park via edX
Learn how to leverage leading tools and approaches to digital marketing data analysis. Dive into SEO and Paid search strategies, web analytics, online testing, machine learning and AI/Big Data applications to strengthen your digital marketing efforts and leverage your resources most effectively.

Excel Power Tools for Data Analysis
Macquarie University via Coursera
Welcome to Excel Power Tools for Data Analysis. In this four-week course, we introduce Power Query, Power Pivot and Power BI, three power tools for transforming, analysing and presenting data.

Data Analysis: Statistical Modeling and Computation in Applications
Massachusetts Institute of Technology via edX
A hands-on introduction to the interplay between statistics and computation for the analysis of real data. — Part of the MITx MicroMasters program in Statistics and Data Science.
★☆☆☆☆ (1 rating)

AWS Cloud Practitioner Essentials
Amazon Web Services via edX
This course will introduce you to cloud concepts and core AWS services, security and architecture to advance your cloud knowledge and solve business challenges.

Machine Learning Data Lifecycle in Production
deeplearning.ai via Coursera
In the second course of Machine Learning Engineering for Production Specialization, you will build data pipelines by gathering, cleaning, and validating datasets and assessing data quality; implement feature engineering, transformation, and selection with TensorFlow Extended and get the most predictive power out of your data; and establish the data lifecycle by leveraging data lineage and provenance metadata tools and follow data evolution with enterprise data schemas.

Bioinformatics for Biologists: An Introduction to Linux, Bash Scripting, and R
Wellcome Genome Campus via FutureLearn
Get familiar with Linux and its command line in order to access the full range of bioinformatics tools available to researchers.

Low-Budget Video Production: Visual Communication for Small Charities
The Open University via FutureLearn
Understand how video can expand and enhance your organisation’s communications and develop practical skills for your productions.

UX Design
HEC Montréal via edX
Master Design Thinking and UX Design through user-centred design to deliver innovative user experiences.

Essentials of Data Science With R Software – 1: Probability and Statistical Inference
Indian Institute of Technology Kanpur via Swayam
Any data analysis is incomplete without statistics. After getting the data, the statistical tools aims to extract the information hidden inside the data.

Cybersecurity Basics
IBM via edX
You will explore information security from its history to a description of various cybercriminals and cybersecurity threats concluding with the tools needed to prevent an attack.

Introduction to Java
LearnQuest via Coursera
This course includes hands-on practice and will give you a solid knowledge of the Java language. After completing this course, you will be able to identify Java’s benefits, program in basic Java syntax using Java data types, and incorporate branches and loops.

JavaScript Basics
University of California, Davis via Coursera
This course introduces the programming language JavaScript and shows the websites that include the type of interactions students will eventually be able to develop. Learners will understand the importance of how JavaScript was developed and why such history impacts the way JavaScript is currently written and in future releases.

MCO-03: Research Methodology and Statistical Analysis
IGNOU via Swayam
The Objective of this course to pay awareness to the most important aspect of Research i.e. Research Methodology. It will enable the Researchers to build up the most suitable methodology for their Research Studies.

Foundations of Modern Finance II
Massachusetts Institute of Technology via edX
Learn fundamental principles of modern finance, including valuation models, methods for risk analysis, derivative instruments and investment management.

Google Workspace Security
Google Cloud via Coursera
In this course you will focus on the various aspects of Google Workspace Security including user password policies and how to enable and enforce two step verification (2SV) for your users.

Aruba Networking Basics
Aruba via Coursera
You will learn what a basic computer network is, compare local and wide area networks, use cases, and implementation types. Communication over these networks relies on protocols. Once you learn about those, you will be well on your way to understanding network communications and well prepared to learn VLANs and how to configure an Aruba OS Switch!

Habilidades de Excel para el negocio: Conceptos básicos
Macquarie University via Coursera
En este primer curso de la especialización de habilidades de Excel para el negocio, aprenderá los conceptos básicos de Microsoft Excel. En seis semanas, podrá navegar, de forma experta, a través de la interfaz de usuario de Excel, realizar cálculos básicos con fórmulas y funciones, dar formato profesional a hojas de cálculo y crear visualizaciones de datos a través de gráficos y cuadros.

Excel for Everyone: Data Management
The University of British Columbia via edX
Further your Excel skills to manage larger datasets and more complex data wrangling, management and modelling.

Introduction to Digital Transformation with Google Cloud
Google Cloud via Coursera
If you want to learn about cloud technology so you can excel in your role and help build the future of your business, then this introductory course on digital transformation is for you.

Online Advertising & Social Media
University of Maryland, College Park via edX
Learn how to develop Online Advertising Ecosystems complete with Social Media/Social Network and Media Big Data analysis for better decision making in all forms of outreach.

Introduction to Web Development with HTML, CSS, JavaScript
IBM via Coursera
Want to take the first steps to become a Cloud Application Developer? This course will lead you through the languages and tools you will need to develop your own Cloud Apps.

Managing Google Workspace
Google Cloud via Coursera
This course focuses on the Google Workspace core services such as Gmail, Calendar, and Drive & Docs. You will become familiar with the various service settings, and learn how to enable them for all or just a subset of your users.

Introduction to Embedded Machine Learning
Edge Impulse via Coursera
This course will give you a broad overview of how machine learning works, how to train neural networks, and how to deploy those networks to microcontrollers.

Mercados financieros
Yale University via Coursera
Una síntesis de las ideas, métodos e instituciones que permiten que la sociedad humana pueda gestionar los riesgos y promover la actividad empresarial.

Arduino para niños ¡vamos al espacio!
The Pontificia Universidad Javeriana via edX
El curso de Arduino está orientado a público infantil y juvenil; los exploradores, es decir, los estudiantes, serán invitados a participar en varias misiones para que una nave espacial llegue a la tierra sana y salva.

Academic English
University of Queensland via edX
A practical and introductory course to build your skills in academic writing.

Analyze Datasets and Train ML Models using AutoML
deeplearning.ai via Coursera
You will learn foundational concepts for exploratory data analysis (EDA), automated machine learning (AutoML), and text classification algorithms.
★★★★☆ (1 rating)

Introduction to Object-Oriented Programming with Java I: Foundations and Syntax Basics
Georgia Institute of Technology via edX
Learn the foundational basics of the Java programming language.