GPT-5.3 Codex Spark

Model details

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GPT-5.3 Codex Spark

Model
gpt-5.3-codex-spark
Provider
openai-codex
API
openai-codex-responses
Base URL
https://chatgpt.com/backend-api
Input
text
Reasoning
Yes
Context window
128,000
Max tokens
128,000
Cost / million input
$0
Cost / million output
$0
Cost / million cache read
$0
Cost / million cache write
$0

Also available from other providers

Model config JSON
{
  "providers": {
    "openai-codex": {
      "apiKey": "YOUR_API_KEY",
      "models": [
        {
          "id": "gpt-5.3-codex-spark",
          "name": "GPT-5.3 Codex Spark",
          "reasoning": true,
          "input": [
            "text"
          ],
          "contextWindow": 128000,
          "maxTokens": 128000,
          "cost": {
            "input": 0,
            "output": 0,
            "cacheRead": 0,
            "cacheWrite": 0
          }
        }
      ],
      "api": "openai-codex-responses",
      "baseUrl": "https://chatgpt.com/backend-api"
    }
  }
}