FindBugs vs SonarQube: What are the differences?
FindBugs: An open-source static code analyser. It detects possible bugs in Java programs. Potential errors are classified in four ranks: scariest, scary, troubling and of concern. This is a hint to the developer about their possible impact or severity; SonarQube: Continuous Code Quality. SonarQube provides an overview of the overall health of your source code and even more importantly, it highlights issues found on new code. With a Quality Gate set on your project, you will simply fix the Leak and start mechanically improving.
FindBugs and SonarQube can be primarily classified as "Code Review" tools.
SonarQube is an open source tool with 3.88K GitHub stars and 1.09K GitHub forks. Here's a link to SonarQube's open source repository on GitHub.