openai
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.
const response = await fetch('https://api.minirouter.sh/v1/chat/completions', { method: 'POST', headers: { Authorization: `Bearer ${process.env.MINIROUTER_KEY}`, 'Content-Type': 'application/json', }, body: JSON.stringify({ model: 'openai/gpt-5.3-codex-fast', messages: [{ role: 'user', content: 'Why is the sky blue?' }], }),}) const data = await response.json()console.log(data.choices[0].message.content)Overview
- Model type
- language
- Context window
- 400,000
- Maximum output
- 128,000
- Input / 1M tokens
- $3.675
- Output / 1M tokens
- $29.4
- Released
- 2026-02-05
Prices include the MiniRouter fee. Compatibility snapshot: 2026-08-06. Input: text, image, pdf. Output: text.
Endpoints
/v1/chat/completions/v1/messages/v1/responsesPlatform-funded routing only. Caller BYOK credentials and OIDC-based upstream authentication are intentionally excluded; authenticate with a MiniRouter bearer key.
Captured parameters: max_tokens, temperature, stop, tools, tool_choice, reasoning, include_reasoning.
API
Use the setup panel above to switch between Chat Completions, Messages, and client configurations. Every snippet keeps the model ID unchanged.
https://api.minirouter.sh/v1openai/gpt-5.3-codex-fastProviders
MiniRouter selects from the configured routes below. Priority is the catalog order, not a latency or availability score.
| Provider | Priority | Input / 1M | Output / 1M | Parameters | Access |
|---|---|---|---|---|---|
vercel | 1 | $3.675 | $29.4 | max_tokens, temperature, stop, tools, tool_choice, reasoning, include_reasoning | MiniRouter balance |