claude-opus-5-5Claude Opus 5.5 is the first model in Anthropic's Claude 5.5 family, released on 22 September 2026, and on APIMODELS it costs $2.40 per 1M input tokens and $12.00 per 1M output — 40% below Anthropic's $4 / $20 list — with prompt-cache reads at $0.12 and cache writes at $3.00. Anthropic's own framing: it performs at the level of Claude Fable 5.1 on most work while costing 40% less to run than Opus 5 on typical workloads, and it is built for long-running agentic coding and knowledge work. The specifications match Fable 5.1: a 1M-token context window, 128K max output, text and image input, and a reliable knowledge cutoff of June 2026. Adaptive thinking is always on and cannot be disabled — you steer depth with the effort parameter (default medium) — and four breaking changes carry over from Fable 5.1: forced tool use returns an error, thinking blocks are tied to the model that produced them, the older computer_20251124 tool is not accepted, and text between tool calls comes back inside thinking blocks. Call it through /v1/messages or the OpenAI-compatible /v1/chat/completions with one key; failed requests are not charged.
View complete API reference with all parameters and examples.
Enable real-time streaming responses with Server-Sent Events.
{
"model": "claude-opus-5-5",
"stream": true,
"max_tokens": 1024,
"messages": [...]
}Enable Claude to use tools and call functions.
{
"model": "claude-opus-5-5",
"max_tokens": 1024,
"tools": [{
"name": "get_weather",
"description": "Get current weather for a location",
"input_schema": {
"type": "object",
"properties": {
"location": {"type": "string", "description": "City name"}
},
"required": ["location"]
}
}],
"tool_choice": {"type": "auto"},
"messages": [{"role": "user", "content": "What's the weather in Tokyo?"}]
}Analyze PDF documents by sending them as base64 encoded content.
{
"model": "claude-opus-5-5",
"max_tokens": 1024,
"messages": [{
"role": "user",
"content": [{
"type": "document",
"source": {
"type": "base64",
"media_type": "application/pdf",
"data": "<base64_encoded_pdf>"
}
}, {
"type": "text",
"text": "Summarize this document."
}]
}]
}Get structured JSON responses that match your schema.
{
"model": "claude-opus-5-5",
"max_tokens": 1024,
"output_format": {
"type": "json_schema",
"schema": {
"type": "object",
"properties": {
"name": {"type": "string"},
"age": {"type": "integer"}
},
"required": ["name", "age"]
}
},
"messages": [{"role": "user", "content": "Extract info: John is 30 years old"}]
}Enable Claude to search the web for up-to-date information.
{
"model": "claude-opus-5-5",
"max_tokens": 1024,
"tools": [{
"type": "web_search_20250305",
"name": "web_search",
"max_uses": 5
}],
"messages": [{"role": "user", "content": "What's the latest news about AI?"}]
}| Parameter | Type | Required | Description |
|---|---|---|---|
| model | string | Yes | Model identifier (e.g., claude-opus-5-5) |
| messages | array | Yes | Array of message objects with role and content |
| max_tokens | integer | Yes | Maximum tokens in the response (1 - 128000) |
| system | string | No | System prompt to set context |
| stream | boolean | No | Enable streaming responses (SSE) |
| temperature | number | No | Sampling temperature (0.0 - 1.0) |
| top_p | number | No | Nucleus sampling threshold (0.0 - 1.0) |
| top_k | integer | No | Top-k sampling (0 - infinity) |
| stop_sequences | array | No | Sequences that stop generation |
| tools | array | No | Function calling tools definition |
| tool_choice | object | No | Tool selection strategy (auto/any/tool) |
| thinking | object | No | Enable extended thinking mode |
| output_format | object | No | Structured output with JSON schema |
View complete API reference with streaming, thinking, and more.
Billing: Cost = (input_tokens * input_price + output_tokens * output_price) / 1,000,000
$2.40 / $12.00 per 1M tokens against Anthropic's $4 / $20 list; cache reads $0.12
Anthropic: Fable 5.1-level results on most work, 40% cheaper to run than Opus 5
Same window as Fable 5.1; text and image input; knowledge cutoff June 2026
Cannot be disabled — steer depth with effort (default medium); forced tool use now errors
Claude Opus 5.5 is a Large Language Model API provided by Anthropic. Claude Opus 5.5 is the first model in Anthropic's Claude 5.5 family, released on 22 September 2026, and on APIMODELS it costs $2.40 per 1M input tokens and $12.00 per 1M output — 40% below Anthropic's $4 / $20 list — with prompt-cache reads at $0.12 and cache writes at $3.00. Anthropic's own framing: it performs at the level of Claude Fable 5.1 on most work while costing 40% less to run than Opus 5 on typical workloads, and it is built for long-running agentic coding and knowledge work. The specifications match Fable 5.1: a 1M-token context window, 128K max output, text and image input, and a reliable knowledge cutoff of June 2026. Adaptive thinking is always on and cannot be disabled — you steer depth with the effort parameter (default medium) — and four breaking changes carry over from Fable 5.1: forced tool use returns an error, thinking blocks are tied to the model that produced them, the older computer_20251124 tool is not accepted, and text between tool calls comes back inside thinking blocks. Call it through /v1/messages or the OpenAI-compatible /v1/chat/completions with one key; failed requests are not charged. Through APIMODELS platform, you can access this model via a unified API with transparent pay-as-you-go pricing. Current pricing: Input: $2.40, Output: $12.00 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.
Claude Opus 5.5 is available through APIMODELS at: Input: $2.40, Output: $12.00 per 1M tokens. Billing is pay-as-you-go — you only pay for what you generate.
Sign up at APIMODELS, get your API key, and call our unified API endpoint. We provide detailed API documentation with code examples in cURL, Python, and Node.js.
APIMODELS offers the same Claude Opus 5.5 model 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.
$2.40 per 1M input tokens and $12.00 per 1M output, with cache reads at $0.12 and cache writes at $3.00. Anthropic lists $4 / $20 with cache reads at $0.20, so we are 40% below. Billing is per actual token, failed requests are free, and there is no monthly minimum.
Anthropic's own positioning: Opus 5.5 performs at the level of Fable 5.1 on most work while costing 40% less to run than Opus 5 on typical workloads. Here Opus 5.5 is $2.40 / $12.00, Opus 5 is $3 / $15 and Fable 5.1 is $5 / $25 — unless you have verified that a task only comes out right on Fable 5.1, starting on Opus 5.5 is the better default. All three share the same specs: 1M context, 128K output.
Change the model name to claude-opus-5-5, then watch four breaking changes: adaptive thinking is always on and can no longer be disabled (steer depth with effort, default medium); forced tool use — tool_choice naming a specific tool — returns an error; thinking blocks are tied to the model that produced them, so a conversation cannot carry old thinking blocks across models; and the older computer_20251124 tool is not accepted. Text between tool calls also comes back inside thinking blocks, so apps that stream it as progress need to set display.
Both work: the native Anthropic POST https://api.apimodels.app/v1/messages, or the OpenAI-compatible /v1/chat/completions, with model claude-opus-5-5 and Authorization: Bearer your apimodels key. Streaming, tool calling and image input are supported; prompt caching follows Anthropic's cache_control usage and hits bill at $0.12.
On APIMODELS, Claude Opus 5.5 runs alongside 60+ models on one API key and one balance, so choosing is about fit, not lock-in. It supports 40% Below Official, 1M Context, Agentic Coding, Adaptive Thinking, and you can weigh it on price and capability against other Large Language Model models, then switch by changing a single model-name string — no new account or integration. Browse every Large Language Model option with live pricing at apimodels.app/models.
Claude Opus 5.5 supports: 40% Below Official, 1M Context, Agentic Coding, Adaptive Thinking. See the APIMODELS docs for full parameters and call examples.
Yes. APIMODELS exposes Claude Opus 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.
We support Stripe (Visa, Mastercard, and other international cards) and Alipay. Credits are available instantly after payment.