what is it? How do I use it?
SonarLint is a Free and Open Source IDE extension that identifies and helps you fix quality and security issues as you code. Like a spell checker, SonarLint squiggles flaws and provides real-time feedback and clear remediation guidance to deliver clean code from the get-go. 
Go to the Main SonarLint page and click the “Install SonarLint for Free” button