GPT-5.3-Codex

Approved Data Classifications

Description

GPT-5.3-Codex is OpenAI's coding-optimized model for long-horizon, agentic software tasks. It is an upgraded version of GPT-5.3 for Codex and similar coding environments, supports reasoning.effort settings (low, medium, high, and xhigh), and accepts text and image input with text output. The model provides a 400,000-token context window with up to 128,000 output tokens and a Sep 30, 2025 knowledge cutoff. Pricing is $2.20 per 1M input tokens, $17.60 per 1M output tokens, and $0.22 per 1M cached input tokens.

Capabilities

Model	Knowledge Cutoff	Input	Output	Context Length	Cost (per 1 million tokens)
gpt-5.3-codex	Aug 31 2025	Text, Image, Pdf	Text	400,000	$2.20/1M input $17.60/1M output

info

• 1M represents 1 Million Tokens
• All prices listed are based on 1 Million Tokens
• Cached input: $0.22 per 1M tokens

Availability

Cloud Provider

Usage

curl

curl -X POST https://api.ai.it.ufl.edu/v1/chat/completions \
-H "Content-Type: application/json" \
-H "Authorization: Bearer <API_TOKEN>" \
-d '{
    "model": "gpt-5.3-codex",
    "messages": [
        {
            "role": "system",
            "content": "You are a helpful assistant."
        },
        {
            "role": "user",
            "content": "Write a haiku about an Alligator."
        }
    ]
}'

python

from openai import OpenAI

client = OpenAI(
    api_key="your_api_key",
    base_url="https://api.ai.it.ufl.edu/v1"
)

response = client.chat.completions.create(
    model="gpt-5.3-codex", # model to send to the proxy
    messages = [
        { "role": "system", "content": "You are a helpful assistant." },
        {
            "role": "user",
            "content": "Write a haiku about an Alligator."
        }
    ]
)

print(response.choices[0].message)

javascript

import OpenAI from 'openai';

const openai = new OpenAI({
  apiKey: 'your_api_key',
  baseURL: 'https://api.ai.it.ufl.edu/v1'
});

const completion = await openai.chat.completions.create({
    model: "gpt-5.3-codex",
    messages: [
        { role: "system", content: "You are a helpful assistant." },
        {
            role: "user",
            content: "Write a haiku about an Alligator.",
        },
    ],
});

print(completion.choices[0].message)

---

References

1. OpenAI GPT-5.3-Codex Model
   https://platform.openai.com/docs/models/gpt-5.3-codex
2. OpenAI API Pricing
   https://openai.com/api/pricing/