Polymer - Polymer is a library that uses the latest web technologies to let you create custom HTML elements.
HackerPen - What is HackerPen?
Kula - Your outbound hiring challenges, automated
HackerRank - HackerRank is a platform that allows companies to conduct interviews remotely to hire developers and for technical assessment purposes.
Techintern.io - Hire the best software developer students
HackerEarth - HackerEarth is the network of top developers across the world. They connect to start-ups, tech companies, organizations and discover the best developer jobs. They participate in programming challenges and compete against other top developers.