QuizUp - QuizUp gives you the opportunity to test your trivia skills against friends and strangers throughout the world.

Codacy - Automatically reviews code style, security, duplication, complexity, and coverage on every change while tracking code quality throughout your sprints.

A Google a Day - Online trivia game where you use Google's search to answer questions as fast as you can.

SonarQube - SonarQube, a core component of the Sonar solution, is an open source, self-managed tool that systematically helps developers and organizations deliver Clean Code.

Trivia Crack Kingdoms - The amazing quiz game that lets you test your knowledge and challenge your friends to see who is the smartest. Developed by Etermax

CodeClimate - Code Climate provides automated code review for your apps, letting you fix quality and security issues before they hit production. We check every commit, branch and pull request for changes in quality and potential vulnerabilities.