GPT-5.4 Pro
Access GPT-5.4 Pro through one API key. OpenAI's most powerful reasoning model.
OpenAI's most powerful reasoning model. Extended thinking, 100K output tokens, and top-tier performance on complex multi-step problems.
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-5.4 Pro respond in real time.
Maximum tokens in the response.
Real-time tokens
Context Window
1.1M tokens
Max Output
100K tokens
Input Price
$42.00 / 1M tokens
Output Price
$252.00 / 1M tokens
Strengths
OpenAI's most powerful reasoning model, using extended internal thinking to solve hard multi-step problems in math, science, and complex analysis.
Returns up to 100,000 output tokens in a single call — the largest output ceiling in this lineup — enough for long proofs, full reports, or large code generations.
Built for the hardest tasks: rigorous multi-step derivations, deep research synthesis, and problems where lesser models break down or skip steps.
A roughly 1,050,000-token context window ingests very large documents and codebases so its extended reasoning can operate over complete context.
Quick start
Copy this snippet and start making calls with GPT-5.4 Pro.
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-5.4-pro",
"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-5.4 Pro through YepAPI?
GPT-5.4 Pro API — pricing, context window & access
GPT-5.4 Pro is OpenAI's most powerful reasoning model, built around extended thinking for the hardest multi-step problems. It pairs a ~1M-token context window with an exceptional 100,000-token output ceiling, the largest in this lineup.
Through YepAPI you reach GPT-5.4 Pro over an OpenAI-compatible endpoint with one key that also covers Claude, Gemini, Grok, Qwen, Mistral, and Perplexity Sonar, plus SEO, SERP, and web-scraping endpoints.
What is GPT-5.4 Pro?
GPT-5.4 Pro is OpenAI's flagship reasoning model. It is a reasoning model — it spends extended internal compute thinking through a problem before answering — which makes it markedly stronger on hard, multi-step tasks than standard chat models, at the cost of higher latency and price. It carries a context window of about 1,050,000 tokens and can return up to 100,000 output tokens, so it can both read and produce very large content. It is the model for problems where correctness on difficult reasoning outweighs everything else.
Build with GPT-5.4 Pro via YepAPI
Call GPT-5.4 Pro through YepAPI's OpenAI-compatible /v1/ai/chat endpoint with the model set to gpt-5.4-pro. Your OpenAI SDK code works after changing the base URL and model name. Because it is expensive, the usual pattern is to handle routine work with a cheap model and escalate only the hardest requests to GPT-5.4 Pro — a one-string switch on the same key that reaches every model.
GPT-5.4 Pro API pricing — $42.00 / $252.00 per 1M tokens
GPT-5.4 Pro costs $42.00 per 1M input tokens and $252.00 per 1M output tokens on YepAPI — by far the highest rate in this lineup, reflecting its extended-reasoning compute. Note that reasoning models consume output tokens for their internal thinking, so bills grow fast; reserve it for problems that justify the cost. Billing is per token with no minimums.
GPT-5.4 Pro for the hardest reasoning problems
GPT-5.4 Pro earns its price only on genuinely hard tasks: rigorous mathematical proofs, scientific and quantitative analysis, deep research synthesis, and complex planning where a wrong step is costly. Its 100K output ceiling supports long derivations and full reports in one call. For everyday work, cheaper models are the right choice; for the few problems that defeat them, GPT-5.4 Pro is the escalation target.
Try GPT-5.4 Pro free
New YepAPI accounts get $5 in free credit with no card required. Given GPT-5.4 Pro's high rates, $5 covers a focused test on a hard problem or two — enough to see whether its extended reasoning clears tasks your current model can't.
Start generating in 30 seconds
$5 free credit on signup. No credit card required. Pay per call.
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 most powerful reasoning model. Extended thinking, 100K output tokens, and top-tier performance on complex multi-step problems.
Input tokens cost $42.00 per 1M tokens and output tokens cost $252.00 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-5.4 Pro supports a 1.1M token context window with up to 100K output tokens per request.
Ready to use GPT-5.4 Pro?
$5 free credit on signup. No credit card required. Pay per call.
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