coala-bears are routines used by coala package to check lints and fix issue if found.
coala-bears are routines for defining certain quality requirements in various languages. Many of these plugins for various languages are shipped along with coala (coala: Language Independent Code Analysis)
The checking routines are named Bears in coala. You can easily define a simple project file to check your project with all bears either shipped with coala or ones you found in the internet and trust.