OpenAI: GPT-5.3 Codex

Quickstart

Use your Moduck API Key, set the API base URL to https://api.moduck.ai/v1, and set the model parameter to moduck/openai/gpt-5-3-codex.

import os
import requests

base_url = "https://api.moduck.ai/v1"
api_key = os.environ["MODUCK_API_KEY"]
model_id = "moduck/openai/gpt-5-3-codex"

response = requests.post(
    f"{base_url}/chat/completions",
    headers={
        "Authorization": f"Bearer {api_key}",
        "Content-Type": "application/json",
    },
    json={
        "model": model_id,
        "messages": [{"role": "user", "content": "Hello!"}],
        "stream": False,
    },
    timeout=60,
)
response.raise_for_status()
print(response.json())

Use the familiar OpenAI-style chat request format to make model integration easier.

GPT-5.3 Codex API Pricing

Benchmarks

Performance

Measured on the Moduck gateway across live traffic, hour by hour over the last 24 hours. Time to first token is how long before anything appears; throughput is how fast the answer is written after that; end-to-end latency is the whole round trip. Figures are medians unless the card says otherwise.

Artificial Analysis measurement · Xhigh

Availability

Uptime is the share of time at least one provider serving this model responded. Availability is stricter: the share of requests actually served. A provider that answers but fails part of the traffic lowers availability without lowering uptime. Both cover the last three days.

GPT-5.3 Codex Compare models

Model specifications

Input

text, image, pdf

Output

text

Context window

400,000

Maximum input

272,000

Maximum output

128,000

Release date

2026-02-05

Attachments

Yes

Reasoning

Yes

Tool calling

Yes

Structured output

Yes

Temperature setting

Yes

Open weights

No

Frequently asked questions

Related models

GPT-5.2 CodexOpenAIInputUSD 1.4 / 1M tokensOutputUSD 11.2 / 1M tokensView model