The Java Concolic Unit Testing Engine (jCUTE) automatically generates unit tests for Java programs. Concolic execution combines randomized concrete execution with symbolic execution and automatic constraint solving. Symbolic execution allows jCUTE to discern inputs that lead down different execution paths; randomized concrete execution helps it overcome limitations of the constraint solver, like the inability to analyze system calls or solve general systems of non-linear integer equations. Through this combination, jCUTE is able to generate test cases that execute many different execution paths in real Java programs. jCUTE supports multi-threaded programs. It can discover race conditions and deadlocks through systematic schedule exploration.