LeetCode: Offers a vast array of coding problems and challenges, from easy to hard, with detailed solutions and community discussions.
HackerRank: Provides coding challenges and competitions across various domains such as algorithms, data structures, and artificial intelligence.
Codewars: Features a wide range of coding katas (challenges) that help improve coding skills through practice and community collaboration.
Codecademy: Provides interactive courses and projects in various programming languages to build and practice coding skills.
Exercism: Offers coding exercises with mentoring from experienced developers to help you improve your programming skills.
TopCoder: Hosts competitive programming contests and provides practice problems to enhance problem-solving and coding abilities.
Project Euler: Focuses on mathematical and computational problems that require creative coding solutions, ideal for advanced learners.