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GPT 5.3 Codex (Fast)

GPT-5.3-Codex advances both the frontier coding performance of GPT‑5.2-Codex and the reasoning and professional knowledge capabilities of GPT‑5.2, together in one model, which is also 25% faster. This enables it to take on long-running tasks that involve research, tool use, and complex execution. Your use is subject to OpenAI's Terms & Privacy Policies.

ReasoningTool UseFile InputVision (Image)Web SearchImplicit CachingWebsockets
Use with AI GatewayView docs
import { streamText } from 'ai'


const result = streamText({
  model: 'openai/gpt-5.3-codex-fast',
  prompt: 'Why is the sky blue?'
})
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P50 time to first token (TTFT) on live AI Gateway traffic, in milliseconds. View the docs for more info.