GPT-5.3-Codex
OpenAI
openai/gpt-5.3-codexGPT-5.3-Codex is OpenAI's February 2026 Codex-native coding agent, pairing frontier coding performance with general reasoning for long-horizon, real-world engineering work. It supports steering the agent mid-task and is notable as a model OpenAI used to help build itself.
Cost rate
2.5x
Context
400K
Released
Feb 24, 2026
Input
TextImageFile
Output
Text
Support
ReasoningTool callingStructured outputs