GPT-5.1 Codex Max
Access GPT-5.1 Codex Max through one API key. Max-output coding model.
OpenAI's earlier generation max-output coding model. 128K output tokens for generating entire codebases.
No credit card required. Takes 30 seconds.
2,400+
Developers
1.2M+
API calls served
100+
Endpoints
$0.01
Per call
Yep, that's it.
Try it live
Send a message and see GPT-5.1 Codex Max respond in real time.
Maximum tokens in the response.
Real-time tokens
Context Window
400K tokens
Max Output
128K tokens
Input Price
$1.25 / 1M tokens
Output Price
$10.00 / 1M tokens
Strengths
Quick start
Copy this snippet and start making calls with GPT-5.1 Codex Max.
const res = await fetch('https://api.yepapi.com/v1/ai/chat', {
method: 'POST',
headers: {
'x-api-key': 'YOUR_API_KEY',
'Content-Type': 'application/json',
},
body: JSON.stringify({
"model": "openai/gpt-5.1-codex-max",
"messages": [
{
"role": "user",
"content": "Explain API gateways in 2 sentences."
}
],
"maxTokens": 256
}),
});
const { data } = await res.json();
console.log(data.message.content);Why use GPT-5.1 Codex Max through YepAPI?
What developers say
“Switched from SerpAPI and cut our SERP costs by 80%. Same data quality, way simpler billing.”
“One API key for AI models, SERP data, and web scraping. Saved us from managing 4 separate providers.”
“The $5 free credit let us prototype our entire rank tracking feature before committing. No other API does that.”
Frequently asked questions
OpenAI's earlier generation max-output coding model. 128K output tokens for generating entire codebases.
Input tokens cost $1.25 per 1M tokens and output tokens cost $10.00 per 1M tokens through YepAPI. No monthly minimums — you only pay for what you use.
Sign up for a free API key, then send requests to the /v1/ai/chat endpoint.
GPT-5.1 Codex Max supports a 400K token context window with up to 128K output tokens per request.
Ready to use GPT-5.1 Codex Max?
$5 free credit on signup. No credit card required. Pay per call.
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