Software developers not only need to stay up to date with modern technologies, frameworks, or libraries. They need to learn and practice their skills. There are many websites with free or paid programming courses, but where to practice coding skills? Here is a bunch of useful websites that allow you to solve little problems using your favourite programming languages.
Sphere Online Judge (SPOJ)
SPOJ is one of the biggest websites with programming exercises. It offers rankings and organizes contests.
Codewars
Codewars is a platform that helps you learn, train, and improve your coding skills by solving programming tasks of many types and difficulty levels. You choose how you would like to learn. Do you want to take on increasingly difficult challenges? Maybe you prefer training through repetition and by improving your solutions. After solving a task, compare your answer with other users and learn from them or help less experienced users by answering their questions.
Coderbyte
Coderbyte is an application built to help practice programming and improve coding skills. It offers a collection of code challenges and web development courses that can help prepare for upcoming job interviews. The coding challenges range in difficulty and they can all be completed straight in the online editor.
CodeChef
CodeChef is one of the world’s largest and popular global competitive programming platforms. CodeChef promotes constant learning and friendly programming competitions for its users, along with the support of its large community of problem curators.
CheckiO
Coding games for beginners and advanced programmers where you can improve your coding skills by solving engaging challenges and fun tasks using Python and TypeScript.
Codeforces
Codeforces is a training and learning platform, a social network dedicated to programming and programming contests. Contests are held regularly, the participant's skills are reflected by their rating.
Exercism
Exercism aims to provide opportunities for people of all backgrounds by helping them develop their programming skills through practice and mentorship.
CodinGame
The goal of the CodinGame is to let programmers keep on improving their coding skills by solving the World's most challenging problems, learn new concepts, and get inspired by the best developers.
HackerEarth
Sharpen your coding skills, prepare for interviews or compete in coding challenges along with a community.
LeetCode
LeetCode is a platform to help you enhance your skills, expand your knowledge and prepare for technical interviews.
Code & Conquer
Code & Conquer is a turn-based multiplayer strategy game designed to be played by bots. You code the Artificial Intelligence and earn badges.
Advent of Code
Advent of Code is an Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like. People use them as a speed contest, interview prep, company training, university coursework, practice problems, or to challenge each other
Project Euler
Project Euler is a series of challenging mathematical/computer programming problems.
ProgrammingPraxis
A simple website with programming exercises without any contests, any points, and without any awards.
CodeAbbey
CodeAbbey is created to provide short programming problems for all who want to learn programming and improve their programming skills.
The Python Challenge
Here is a little very old website with 33 problems to solve. The main focus is put on Python language.
r/dailyprogrammer
Reddit community for sharing programming challenges. For learning, refreshing, or just for fun!