You can now access OpenAI's latest Codex models, GPT-5.1 Codex Max with Vercel's AI Gateway and no other provider accounts required.
GPT-5.1 Codex Max is faster and more token efficient compared to previous Codex models, optimized for long-running coding tasks, and can maintain context and reasoning over long periods without needing to start new sessions.
To use GPT-5.1 Codex Max with the AI SDK, set the model to openai/gpt-5.1-codex-max.
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 observability, Bring Your Own Key support, and intelligent provider routing with automatic retries.
Learn more about AI Gateway, view the AI Gateway model leaderboard or try it in our model playground.