During maintenance, software is modified and evolved to enhance its functionality, eliminate faults, and adapt it to changed or new platforms. In this demo, we present BERT, a tool for helping developers identify regression faults that they may have introduced when modifying their code. BERT is based on the concept of behavioral regression testing: given two versions of a program, BERT identifies behavioral differences between the two versions through dynamic analysis, in three steps. First, it generates a large number of test inputs that focus on the changed parts of the code. Second, it runs the generated test inputs on the old and new versions of the code and identifies differences in the tests' behavior. Third, it analyzes the identified differences and presents them to the developers. By focusing on a subset of the code and leveraging differential behavior, BERT can provide developers with more detailed information than traditional regression testing approaches - -approaches that rely exclusively on existing test suites, which may be limited in scope and may not adequately test the changes in a program. BERT is implemented as a plug-in for Eclipse, a popular Integrated Development Environment, and is freely available. This demo presents BERT, its underlying technology, and examples of its usage.