From securityonline.info

echidna

Echidna is a weird creature that eats bugs and is highly electrosensitive (with apologies to Jacob Stanley)

More seriously, Echidna is a Haskell library designed for fuzzing/property-based testing of EVM code. It supports relatively sophisticated grammar-based fuzzing campaigns to falsify a variety of predicates.

Features

Generates inputs tailored to your actual code
Optional coverage guidance to find deeper bugs
Automatic testcase minimization for quick triage
Seamless integration into the development workflow
Fast
Powerful API for advanced usage
Beautiful logo