codeforces. programming competitions and contests, programming community

CodeChef | CodeChef: Practical coding for everyone

hackerrank is the market-leading technical assessment and remote interview solution for hiring developers. learn how to hire technical talent from anywhere!

a website dedicated to the fascinating world of mathematics and programming

the goal of this project is to translate the wonderful resource http://e-maxx.ru/algo which provides descriptions of many algorithms and data structures especially popular in field of competitive programming. moreover we want to improve the collected knowledge by extending the articles and adding new articles to the collection.

Stack Overflow | The World’s Largest Online Community for Developers

AtCoder is a programming contest site for anyone from beginners to experts. We hold weekly programming contests online.

sourceforge provides free & fast open source software downloads and development, and business software reviews and comparisons featuring the largest open source and business software directory.

well organized and easy to understand web building tutorials with lots of examples of how to use html, css, javascript, sql, python, php, bootstrap, java, xml and more.