gpt-5.4-xhighGPT-5.4 with the deepest reasoning effort. The model spends most of its output budget thinking before answering — for the hardest debugging, design, and analysis tasks. Same per-token price as base GPT-5.4; reasoning tokens are billed as output_tokens.
reasoning.effort = xhigh upstream — for the hardest problems
Hard debugging, cross-file analysis, multi-step planning
Reasoning tokens count as output_tokens at base GPT-5.4 rate
Drop-in via wire_api = "responses" + model = "gpt-5.4-xhigh"
View complete API reference with all parameters and examples.
Enable real-time streaming responses with Server-Sent Events.
{
"model": "gpt-5.4-xhigh",
"stream": true,
"messages": [...]
}Enable the model to use tools and call functions.
{
"model": "gpt-5.4-xhigh",
"tools": [{
"type": "function",
"function": {
"name": "get_weather",
"description": "Get current weather for a location",
"parameters": {
"type": "object",
"properties": {
"location": {"type": "string", "description": "City name"}
},
"required": ["location"]
}
}
}],
"messages": [{"role": "user", "content": "What's the weather in Tokyo?"}]
}Get structured JSON responses from the model.
{
"model": "gpt-5.4-xhigh",
"response_format": {"type": "json_object"},
"messages": [{"role": "user", "content": "Extract info as JSON: John is 30 years old"}]
}| Parameter | Type | Required | Description |
|---|---|---|---|
| model | string | Yes | Model identifier (e.g., gpt-5.4-xhigh) |
| messages | array | Yes | Array of message objects with role and content |
| max_tokens | integer | No | Maximum tokens in the response |
| stream | boolean | No | Enable streaming responses (SSE) |
| temperature | number | No | Sampling temperature (0.0 - 2.0) |
| top_p | number | No | Nucleus sampling threshold (0.0 - 1.0) |
| tools | array | No | Function calling tools definition |
| response_format | object | No | Output format (e.g., json_object) |
View complete API reference with streaming, thinking, and more.
Billing: Cost = (input_tokens * input_price + output_tokens * output_price) / 1,000,000
GPT-5.4 (xhigh reasoning) is a Large Language Model API provided by OpenAI. GPT-5.4 with the deepest reasoning effort. The model spends most of its output budget thinking before answering — for the hardest debugging, design, and analysis tasks. Same per-token price as base GPT-5.4; reasoning tokens are billed as output_tokens. Through API Models platform, you can access this model via a unified API at prices significantly lower than official rates. Current pricing: Input: $0.552, Output: $4.412 per 1M tokens.
Build intelligent conversational systems to automatically answer user queries and improve service efficiency.
Automatically write articles, emails, ad copy, and other text content to boost productivity.
Assist with code writing, debugging, and code review to accelerate software development.
Understand and analyze unstructured data, extract key insights, and generate summary reports.
GPT-5.4 (xhigh reasoning) is available through API Models at: Input: $0.552, Output: $4.412 per 1M tokens. This is up to 95% cheaper than official pricing.
Sign up at API Models, get your API key, and call our unified API endpoint. We provide detailed API documentation with code examples in cURL, Python, and Node.js.
API Models offers the same GPT-5.4 (xhigh reasoning) model at 60-95% lower cost through our aggregation platform. We provide a unified API interface so you do not need separate accounts for each provider - one API key to access all models.
We support Stripe (Visa, Mastercard, and other international cards) and Alipay. Credits are available instantly after payment.