Diffblue

Diffblue is an Oxford, UK software company that builds Diffblue Cover, an autonomous AI agent that writes and maintains Java unit tests. Spun out of the University of Oxford in 2016, the company uses reinforcement learning rather than large language models alone to generate test suites at scale, targeting large enterprises - including several of the biggest U.S. banks - that need to raise code coverage, modernize legacy Java applications, and ship software with fewer defects.