OpenAI: GPT-5.3 Codex
openai/gpt-5.3-codex
Access GPT-5.3 Codex from OpenAI using Puter.js AI API.
Get Started// npm install @heyputer/puter.js
import { puter } from '@heyputer/puter.js';
puter.ai.chat("Explain quantum computing in simple terms", {
model: "openai/gpt-5.3-codex"
}).then(response => {
document.body.innerHTML = response.message.content;
});
<html>
<body>
<script src="https://js.puter.com/v2/"></script>
<script>
puter.ai.chat("Explain quantum computing in simple terms", {
model: "openai/gpt-5.3-codex"
}).then(response => {
document.body.innerHTML = response.message.content;
});
</script>
</body>
</html>
# pip install openai
from openai import OpenAI
client = OpenAI(
base_url="https://api.puter.com/puterai/openai/v1/",
api_key="YOUR_PUTER_AUTH_TOKEN",
)
response = client.chat.completions.create(
model="openai/gpt-5.3-codex",
messages=[
{"role": "user", "content": "Explain quantum computing in simple terms"}
],
)
print(response.choices[0].message.content)
curl https://api.puter.com/puterai/openai/v1/chat/completions \
-H "Content-Type: application/json" \
-H "Authorization: Bearer YOUR_PUTER_AUTH_TOKEN" \
-d '{
"model": "openai/gpt-5.3-codex",
"messages": [
{"role": "user", "content": "Explain quantum computing in simple terms"}
]
}'
Model Card
GPT-5.3 Codex is OpenAI's most capable agentic coding model, combining frontier coding performance with strong general reasoning and professional knowledge capabilities. It was the first model instrumental in creating itself, having been used to debug its own training and manage its own deployment. It sets state-of-the-art on SWE-Bench Pro and Terminal-Bench while being 25% faster than its predecessor.
Context Window 128K
tokens
Max Output 128K
tokens
Input Cost $1.75
per million tokens
Output Cost $14
per million tokens
Input text, image
modalities
Tool Use Yes
Knowledge Cutoff Aug 31, 2025
Release Date Feb 24, 2026
Output Speed 83
tokens / sec
Latency 82.74s
time to first token
Model Playground
Try GPT-5.3 Codex instantly in your browser.
This playground uses the Puter.js AI API — no API keys or setup required.
Benchmarks
How GPT-5.3 Codex performs on standard evaluations.
| Benchmark | Score |
|---|---|
| GPQA Diamond Graduate-level science Q&A | 91.5% |
| Humanity's Last Exam Cross-domain reasoning | 39.9% |
| SciCode Scientific programming | 53.2% |
| IFBench Instruction following | 75.4% |
| LCR Long-context reasoning | 74.0% |
| Terminal-Bench Hard Agentic terminal tasks | 53.0% |
| τ²-Bench Tool use / agents | 86.0% |
Scores sourced from Artificial Analysis.
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Frequently Asked Questions
You can access GPT-5.3 Codex by OpenAI through Puter.js AI API. Include the library in your web app or Node.js project and start making calls with just a few lines of JavaScript — no backend and no configuration required. You can also use it with Python or cURL via Puter's OpenAI-compatible API.
Yes, it is free if you're using it through Puter.js. With the User-Pays Model, you can add GPT-5.3 Codex to your app at no cost — your users pay for their own AI usage directly, making it completely free for you as a developer.
| Price per 1M tokens | |
|---|---|
| Input | $1.75 |
| Output | $14 |
GPT-5.3 Codex was created by OpenAI and released on Feb 24, 2026.
GPT-5.3 Codex supports a context window of 128K tokens. For reference, that is roughly equivalent to 256 pages of text.
GPT-5.3 Codex can generate up to 128K tokens in a single response.
GPT-5.3 Codex has a knowledge cutoff date of Aug 31, 2025. This means the model was trained on data available up to that date.
GPT-5.3 Codex accepts the following input types: text, image. It produces: text.
Yes, GPT-5.3 Codex supports tool use (function calling), allowing it to interact with external tools, APIs, and data sources as part of its response flow.
GPT-5.3 Codex scores 53.6 on the Artificial Analysis Intelligence Index, outperforming 98% of tracked models. On coding, it scores 53.1 (outperforms 98% of models).
Yes — the GPT-5.3 Codex API works with any JavaScript framework, Node.js, or plain HTML through Puter.js. Just include the library and start building. See the documentation for more details.
Get started with Puter.js
Add GPT-5.3 Codex to your app without worrying about API keys or setup.
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