HackerRank - HackerRank is a platform that allows companies to conduct interviews remotely to hire developers and for technical assessment purposes.
draw.io - Online diagramming application
iMocha - Make intelligent talent decisions.
LucidChart - LucidChart is the missing link in online productivity suites. LucidChart allows users to create, collaborate on, and publish attractive flowcharts and other diagrams from a web browser.
Codility - Codility provides a SaaS platform with advanced validation, security and protection features to evaluate the skills of software engineers.
PlantUML - PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams.