OpenAI is releasing a new version of GPT-5 to its AI coding agent, Codex. The company says its new model, called GPT-5-Codex, spends its “thinking” time more dynamically than previous models and could spend anywhere from a few seconds to seven hours on a coding task. As a result, it performs better on agentic coding benchmarks. The new model is now rolling out in Codex products — which can be accessed via a terminal, IDE, GitHub, or ChatGPT — to all ChatGPT Plus, Pro, Business, Edu, and Enterprise users. OpenAI says it plans to make the model available to API customers in the future. OpenAI says that GPT-5-Codex outperforms GPT-5 on SWE-bench Verified, a benchmark measuring agentic coding abilities, as well as a benchmark measuring performance on code refactoring tasks from large, established repositories. The company also says it trained GPT-5-Codex for conducting code reviews and asked experience software engineers to evaluate the model’s review comments. The engineers reportedly found GPT-5-Codex to submit fewer incorrect comments, while adding more “high-impact comments.” OpenAI’s Codex product lead Alexander Embiricos said GPT-5-Codex works similarly but has no router under the hood and can adjust for how long to work on a task in real time. Embiricos says this is an advantage compared to a router, which decides how much computational power and time to use on a problem at the outset. Instead, GPT-5-Codex can decide five minutes into a problem that it needs to spend another hour. Embiricos said he’s seen the model take upward of seven hours in some cases.