HackerRank

[2] HackerRank categorizes most of their programming challenges into a number of core computer science domains,[3] including database management, mathematics, and artificial intelligence.

Programmers are then ranked globally on the HackerRank leaderboard and earn badges based on their accomplishments, which is intended to drive competition among users.

[9][10] In December 2019, HackerRank acquired Mimir, a cloud-based service that provides tools for teaching computer science courses.

[11] Their enterprise-side product, HackerRank for Work, is a subscription service that aims to help companies source, screen (CodePair), and hire engineers and other technical employees.

[13] In addition to screening, HackerRank also hosts programming hackathons, referred to as CodeSprints, as a way for companies to source technical candidates.