OpenAI model
GPT-5.3 Codex
GPT-5.3 Codex is a OpenAI model tracked in Sim. It supports a 400k token context window. Pricing starts at $1.75/1M input tokens and $14/1M output tokens. Key capabilities include Tool choice, Structured outputs, Reasoning low, medium, high, xhigh. Best for reasoning-heavy tasks that need more deliberate model control.
Input price$1.75/1M
Cached input$0.175/1M
Output price$14/1M
Context window400k
Max output128k tokens
ProviderOpenAI
UpdatedSep 14, 2026
Best forBest for reasoning-heavy tasks that need more deliberate model control.
TemperatureNot configurable
Reasoning effortlow, medium, high, xhigh
VerbosityNot supported
Thinking levelsNot supported
Structured outputsSupported
Tool choiceSupported
Computer useNot supported
Deep researchNot supported
Memory supportSupported
Max output tokens128k
Frequently asked questions
GPT-5.3 Codex is a OpenAI model available in Sim. GPT-5.3 Codex is a OpenAI model tracked in Sim. It supports a 400k token context window. Pricing starts at $1.75/1M input tokens and $14/1M output tokens. Key capabilities include Tool choice, Structured outputs, Reasoning low, medium, high, xhigh.
