Simplex rethinks software development with Codex

Technology partner Simplex is restructuring its software development operations by deploying ChatGPT Enterprise and Codex across its projects. Following the launch of ChatGPT in 2022, Simplex established an AI center of excellence in 2023 to validate AI-native development processes and establish governance and training. To scale its AI initiatives, the company selected Codex as its primary coding agent and uses it for tasks extending far beyond simple code generation. According to Simplex, Codex handles front and back-end code generation from design documents, creates unit tests, reviews nonfunctional requirements, and fixes issues found during integration testing. The company is also validating automated workflows that run Python scripts from Codex CLI to move continuously from server implementation to end-to-end test fixes. By measuring the quantitative impact of generative AI, Simplex has achieved meaningful time savings across multiple stages of development. Ujihiro notes that the technology enables smaller teams to advance design work, improves review accuracy, and allows senior expertise to be applied more broadly. Rather than replacing each step of the traditional development process one for one, Simplex is redesigning workflows around AI by defining rules up front and relying on repeated integration and automated evaluation. The company emphasizes that transitioning to an AI-first operating model requires treating adoption as a structural change, choosing a primary AI agent, and clearly defining where AI executes work versus where humans retain final accountability.