CodeSignal was originally known for its coding assessments used by top tech companies. It now has 2000 short courses with free certificates.
At the heart of this transformation is Cosmo, an AI tutor that guides you through interactive courses spanning programming, data science, machine learning, and increasingly, professional soft skills.
Since launching its learning platform two years ago, CodeSignal now has more than 3.5 million enrollments, with the top 100 courses having 1.5 million of these.
What sets CodeSignal Learn apart is its emphasis on learning by doing. Rather than watching video lectures, learners engage directly with Cosmo in bite-sized lessons that adapt to their pace and provide instant feedback.
This approach has earned praise from learners. At Class Central, we even wrote an in-depth review of CodeSignal highlighting its effectiveness for building practical coding skills, while its soft skills offerings including the Supercommunicator course demonstrate the platform’s ambitions beyond technical training and interview prep.
CodeSignal runs on a freemium model. You don’t need to pay to use most features including a certificate for each course, but Cosmo interactions are limited in the free version. If you find yourself wanting more AI help or want to submit the exercises more frequently, consider a premium subscription.
25 of the most popular courses are on various aspects and uses of Python, with JavaScript and Java also in the list. Other popular topics are Machine Learning and Prompt Engineering.
Here’s a quick summary of the 100 Top CodeSignal courses, based on the number of enrollments:
- Enrollments range from 5.6K to 40.9K. There are ten courses with over 10K enrollments
- Together, they account for over 1.5M enrollments, with an average of 15.6K enrollments
- Between them, they offer 270+ hours of learning
- Average rating: 4.72/5.0
- 38 courses are beginner level, 52 intermediate, and 10 advanced
- 59 of the Top 100 courses are in Programming, 29 in Computer Science, 6 in Artificial Intelligence, 4 in Data Science, and 2 in Personal Development.
The Top 100 CodeSignal Courses:
- Programming Foundations with Python ★★★★☆(26)
- Introduction to Simple Data Structures in Python
- Mastering Control Structures in Python
- Exploring Iterations and Loops in Python
- Defining and Utilizing Functions in Python
- Revisiting Python Essentials
- Applying Simple Looping in Practice with Python
- Practicing String Operations and Type Conversions in Python
- Mastering Implementation of Advanced Loops in Python
- Python Coding Practice for Technical Interviews
- Hashing, Dictionaries, and Sets in Python
- Sorting and Searching Algorithms in Python
- Linked Lists, Stacks, and Queues in Python
- Understanding and Using Trees in Python
- Mastering Graphs in Python
- Maximized Efficiency in Problem Solving Techniques in Python ★★★★☆(1)
- Multidimensional Arrays and Their Traversal in Python
- Revision of Python HashMaps and Their Use in Practice
- Master Splitting Advanced Tasks into Smaller Pieces with Python
- Master Dictionaries, Two Pointers, and More Algorithms in Python
- Getting Into JavaScript Fundamentals
- Web Development with HTML, CSS, and JavaScript ★★★★★(5)
- Client-side Web Development with React.js ★★★★★(1)
- Server-side Web Development with Node.js and Express.js
- Introduction to Authentication and Authorization
- Introduction to MongoDB
- Basics of Numpy and Pandas with Titanic Dataset ★★★★☆(1)
- Intro to Data Visualization with Titanic
- Intro to Time Series Analysis with Airline Data
- Intro to Unsupervised Machine Learning
- Intro to Data Cleaning and Preprocessing with Titanic
- Deep Dive into Numpy and Pandas with Housing Data
- Introduction to Supervised Machine Learning
- Getting Started with Java ★★★★★(1)
- Learning Simple Data Structures in Java
- Iterations and Loops in Java
- Mastering Debugging with Java
- Java String Manipulation for Beginners
- Writing Functions using Java
- Object-Oriented Programming in Java
- Understanding LLMs and Basic Prompting Techniques ★★★★★(5)
- Engineering Output Size with LLMs
- Journey Into Format Control in Prompt Engineering
- Prompt Engineering for Precise Text Modification
- Advanced Techniques in Prompt Engineering
- Hashing, Dictionaries, and Sets in Java
- Sorting and Searching Algorithms in Java
- Advanced Data Structures – Stacks and Queues in Java
- Fundamental Data Structures – Linked Lists in Java
- Interview Prep – The Last Mile in Python
- Interview Practice with Classic Coding Questions in Python
- Easy Interview Coding Practice in Python ★★★★★(4)
- Getting Deep into Complex Algorithms for Interviews with Python
- Getting Started with JavaScript ★★★★★(1)
- Iterating Over Data in JavaScript ★★★★★(1)
- Learning Simple Data Structures in JavaScript
- String Manipulation for JS Beginners
- Intro to Functions in JavaScript
- Understanding Debugging with JavaScript
- Object-Oriented Programming in JavaScript
- Java HashMaps in Practice: Revision and Application
- Multidimensional Arrays and Their Traversal in Java
- Mastering Algorithms: HashMaps, Two Pointers, and Beyond in Java
- Mastering Task Decomposition in Java
- Maximizing Efficiency in Problem-Solving Techniques in Java
- Intro to JavaScript for React Developers
- Introduction to Web Development in React
- Getting Deeper into React ★★★★★(1)
- Understanding and Using APIs in React
- Routing in React Applications
- Introduction to HTML ★★★★★(14)
- Basics of CSS ★★★★★(3)
- Introduction to JavaScript for Front-End Engineers
- Mastering the DOM API
- Communicating with APIs for Front-End Engineers
- Introduction to Responsive Web Development
- Refactoring Code for Readability and Maintainability
- Backward Compatibility in Software Development
- Interview Practice – Advanced Problem Solving
- Revisiting Software Design Patterns in Python
- Advanced Built-In Data Structures and their Usage
- Intro to SQL with Taylor Swift
- Learning SQL Joins with Taylor Swift
- Mastering SQL Functions and Clauses with Taylor Swift
- Advanced Query Techniques and Conditional Logic in SQL
- Hashing, Dictionaries, and Sets in JS
- Sorting and Searching Algorithms in JS
- Fundamental Data Structures – Linked Lists in JavaScript
- Fundamental Data Structures – Stacks and Queues in JS
- Practicing String Operations and Type Conversions in Java
- Java Coding Practice for Technical Interviews
- Mastering Implementation of Advanced Loops in Java
- Applying Simple Looping in Practice with Java
- Revisiting Java Basics
- Data Cleaning and Preprocessing in Machine Learning
- Foundational Machine Learning Models with Sklearn
- Feature Engineering for Machine Learning
- Intro to Model Optimization in Machine Learning
- Introduction to Neural Networks with TensorFlow
- Generative AI in 2025 – Overview and Practice
CodeSignal is a Class Central partner.
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