LLM Reference
OpenAI API

Using GPT-5.3-Codex on OpenAI API

Implementation guide · Codex · OpenAI

Serverless

OpenAI API exposes GPT-5.3-Codex through model ID gpt-5.3-codex. Use the setup steps, sourced pricing, capabilities, and official provider links below to validate this route before deployment.

Last refreshed 2026-06-10. Next refresh: weekly.

Quick Start

  1. 1
    Create an account at OpenAI API and generate an API key.
  2. 2
    Use the OpenAI API SDK or REST API to call gpt-5.3-codex — see the documentation for request format.
  3. 3
    You'll be billed $1.75/1M input, $14.00/1M output tokens. See full pricing.

Code Examples

Install
pip install openai
API key
OPENAI_API_KEY
Model ID
gpt-5.3-codex

Use the model slug directly, e.g. "gpt-4o" or "gpt-4.1-mini".

import os
from openai import OpenAI

client = OpenAI()  # reads OPENAI_API_KEY from env
response = client.chat.completions.create(
    model="gpt-5.3-codex",
    messages=[{"role": "user", "content": "Hello"}]
)
print(response.choices[0].message.content)

Pricing on OpenAI API

TypePrice (per 1M)
Input tokens$1.75
Output tokens$14.00

Capabilities

VisionReasoningJSON / Tool useStructured OutputsCode ExecutionPrompt CachingBatch API

About GPT-5.3-Codex

Most capable agentic coding model from OpenAI. Optimized for long-horizon, agentic coding tasks in the Codex CLI and API. Note: GPT-5.3-Codex-Spark is a distinct ChatGPT Pro research preview (not API-accessible).

Model Specs

Released2026-02-05
Context400k
ArchitectureDecoder Only
Knowledge cutoff2025-08

Provider

OpenAI API
OpenAI API

OpenAI

San Francisco, California, United States