GPT 5.3 Codex is now available on AI Gateway. GPT 5.3 Codex brings together the coding strengths of GPT-5.2-Codex and the reasoning depth of GPT-5.2 in a single model that's 25% faster and more token-efficient.
Built for long-running agentic work, the model handles research, tool use, and multi-step execution across the full software lifecycle, from debugging and deployment to product documents and data analysis. Additionally, you can steer it mid-task without losing context. For web development, it better understands underspecified prompts and defaults to more functional, production-ready output.
To use this model, set model to openai/gpt-5.3-codex in the AI SDK.
Read the full changelog: