Gamma, along with Kent Beck, co-wrote the JUnit software testing framework which helped create Test-Driven Development and influenced the whole software industry[according to whom?]. He was the development team lead of the Eclipse platform's Java Development Tools (JDT), and worked on the IBM Rational Jazz project.
In 2011 he joined the Microsoft Visual Studio team and leads a development lab in Zürich, Switzerland that has developed the "Monaco" suite of components for browser-based development, found in products such as Azure DevOps Services (formerly Visual Studio Team Services and Visual Studio Online), Visual Studio Code, Azure Mobile Services, Azure Web Sites, and the Office 365 Development tools.[3]