GPT-5 Codex
GPT-5 Codex is a version of GPT-5 optimized for agentic coding, trained with reinforcement learning on real-world coding tasks across diverse environments. It generates code that closely mirrors human style and pull-request preferences, follows instructions precisely, and iteratively runs tests until it achieves passing results. With a 272k token context window, GPT-5 Codex supports structured output and tool use for integration with development workflows. It is built for developers who need reliable code generation with human-like conventions and testing loops baked into the process. As part of the GPT-5 family's evolution in coding, GPT-5 Codex serves as a foundation for agentic coding workflows, with newer variants such as GPT-5.2 Codex and GPT-5.3 Codex offering stronger performance on large-scale code transformations and complex software engineering.
Key info
Benchmarks
Independent benchmark scores — composite indices for reasoning, coding, and math, plus individual eval scores where available.
Available routes
No routes currently available — GPT-5 Codex isn't routed through the Opper gateway right now. It may return.
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