gpt-5-5GPT-5.5 is OpenAI’s advanced reasoning model for agentic coding, knowledge work, scientific research, and complex multi-step task execution. Served via the Responses API (`/v1/responses`) with adjustable reasoning effort (low–xhigh), web search, function calling, and multimodal input. Drop-in for OpenAI Codex CLI with wire_api = "responses".
Frontier reasoning for agentic coding, research, and complex multi-step work
reasoning.effort = low / medium / high / xhigh
Built-in web search or function calling (one per request)
Cached input billed at $0.1 / 1M; reasoning tokens count as output
View complete API reference with all parameters and examples.
Enable real-time streaming responses with Server-Sent Events.
{
"model": "gpt-5-5",
"stream": true,
"messages": [...]
}Enable the model to use tools and call functions.
{
"model": "gpt-5-5",
"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-5-5",
"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-5-5) |
| 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-5.5 is a Large Language Model API provided by OpenAI. GPT-5.5 is OpenAI’s advanced reasoning model for agentic coding, knowledge work, scientific research, and complex multi-step task execution. Served via the Responses API (`/v1/responses`) with adjustable reasoning effort (low–xhigh), web search, function calling, and multimodal input. Drop-in for OpenAI Codex CLI with wire_api = "responses". Through API Models platform, you can access this model via a unified API at prices significantly lower than official rates. Current pricing: Input: $1, Output: $5.5 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-5.5 is available through API Models at: Input: $1, Output: $5.5 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-5.5 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.
GPT-5.5 supports: Agentic Coding, Deep Reasoning, Web Search, Multimodal. See the API Models docs for full parameters and call examples.
Yes. API Models exposes GPT-5.5 through a single unified API and one key — no separate provider accounts, and no need to handle each provider's regional network access yourself.
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