# Anthropic Claude Opus 4.5 API

> Claude Opus 4.5 is Anthropic’s frontier reasoning model optimized for complex software engineering, agentic workflows, and long-horizon computer use. It offers strong multimodal capabilities, competitive performance across real-world coding and reasoning benchmarks, and improved robustness to prompt injection. The model is designed to operate efficiently across varied effort levels, enabling developers to trade off speed, depth, and token usage depending on task requirements. It comes with a new parameter to control token efficiency, which can be accessed using the OpenRouter Verbosity parameter with low, medium, or high. Opus 4.5 supports advanced tool use, extended context management, and coordinated multi-agent setups, making it well-suited for autonomous research, debugging, multi-step planning, and spreadsheet/browser manipulation. It delivers substantial gains in structured reasoning, execution reliability, and alignment compared to prior Opus generations, while reducing token overhead and improving performance on long-running tasks.

Source: https://www.sandbase.ai/models/anthropic/claude-opus-4.5
API reference: https://www.sandbase.ai/models/anthropic/claude-opus-4.5/docs

## Facts

- Provider: Anthropic
- Type: Language model
- Model ID: `anthropic/claude-opus-4.5`
- Price: $5 per 1M input tokens, $25 per 1M output tokens
- Context window: 200K tokens, up to 64K output tokens
- Capabilities: chat, vision, reasoning, structured output, function calling
- Billing: pay per use from one SandBase balance; no provider account or subscription needed

## Call it

- Chat Completions API: `POST https://api.sandbase.ai/v1/chat/completions`
- Messages API: `POST https://api.sandbase.ai/v1/messages`

```bash
curl -X POST https://api.sandbase.ai/v1/chat/completions \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "model": "anthropic/claude-opus-4.5",
  "messages": [
    {
      "role": "user",
      "content": "Hello"
    }
  ],
  "max_tokens": 2048
}'
```

## FAQ

### How do I call Anthropic Claude Opus 4.5 through SandBase?

Create a SandBase API key, then send requests with the model ID "anthropic/claude-opus-4.5" to Chat Completions API (/v1/chat/completions) or Messages API (/v1/messages) at https://api.sandbase.ai. The request examples on this page show the exact payload.

### How much does Anthropic Claude Opus 4.5 cost?

$5 per 1M input tokens and $25 per 1M output tokens, billed per request from your SandBase balance. Discounts, when available, are shown in the pricing on this page.

### What is the context window of Anthropic Claude Opus 4.5?

200K tokens of context, with up to 64K output tokens per response.

### How does Anthropic Claude Opus 4.5 score on benchmarks?

Anthropic Claude Opus 4.5 scores 29.1 on the Artificial Analysis Intelligence Index (v4.3), ranking #45 of 83 models on SandBase. Source: Artificial Analysis, measured as Claude Opus 4.5 (Reasoning).

### Which features does Anthropic Claude Opus 4.5 support?

Anthropic Claude Opus 4.5 supports vision (image input), reasoning, function calling, structured output. See Specifications above for the full list.

### Do I need a separate Anthropic account?

No. One SandBase API key and balance gives you access to Anthropic Claude Opus 4.5 and the other models in the catalog; you do not need to sign up with Anthropic separately.