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GPT-5.3 Codex
OpenAI's code-specialized model. Optimized for code generation, refactoring, and multi-file edits. Supports the Responses API for streaming and tool calling.
Specifications
| Provider | OpenAI |
| Category | Text |
| Context window | 400K tokens |
Pricing (Starter tier)
175.00 credits / 1M input tokens
1,400.00 credits / 1M output tokens
Higher tiers get volume discounts. See tiers
Quick Start
curl -X POST https://query.genx.sh/api/v1/generate \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "gpt-5.3-codex",
"params": {
"prompt": "Refactor this Express app to use Hono with typed middleware"
}
}'
Example Request Body
// POST /api/v1/generate
{
"model": "gpt-5.3-codex",
"params": {
"prompt": "Refactor this Express app to use Hono with typed middleware"
}
}