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 in the AI SDK.openai/gpt-5.3-codex AI Gateway provides a unified API for calling models, tracking usage and cost, and configuring retries, failover, and performance optimizations for higher-than-provider uptime. It includes built-in , support, and intelligent provider routing with automatic retries.observabilityBring Your Own Key Learn more about , view the or try it in our .AI GatewayAI Gateway model leaderboardmodel playground Read more