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Anthropic

Claude Sonnet 5.5 API

Upgraded Sonnet-class model for agentic coding, tool use and everyday professional work — faster than Claude Sonnet 5.

Get API KeyDocumentation

Starting at

$0.9

input price per 1M tokens

4 token price options

Claude Sonnet 5.5 playground

Input

anthropic
2048
1.0
1.00

Input

$0.9 / 1M

Output

$4.5 / 1M

Output

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Ask Claude Sonnet 5.5 anything. Messages are sent directly to the API and charged by token usage.

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Claude Sonnet 5.5 API pricing

OptionPrice per 1M tokens
input$0.9
output$4.5
cacheRead$0.09
cacheWrite$1.13

Quick start

Full API reference →
1curl -X POST https://api.api-stock.com/api/v1/messages \
2  -H "Authorization: Bearer $API_STOCK_KEY" \
3  -H "Content-Type: application/json" \
4  -d '{
5    "model": "claude-sonnet-5-5",
6    "max_tokens": 1024,
7    "messages": [
8      {
9        "role": "user",
10        "content": "A cinematic shot of a city at dusk"
11      }
12    ]
13  }'

Frequently asked questions

How much does Claude Sonnet 5.5 cost?

Claude Sonnet 5.5 starts at $0.9 per 1M input tokens through the API Stock API. You pay per use from a single prepaid balance — there is no subscription — and the final price scales with parameters such as resolution or duration.

How do I get an API key for Claude Sonnet 5.5?

Sign up for API Stock, top up your balance by any amount and create an API key in the dashboard — it takes a couple of minutes and needs no contract. The same key works with every model in the catalog, so there is no separate key to obtain for Claude Sonnet 5.5.

How do I call the Claude Sonnet 5.5 API?

Send a POST request to https://api.api-stock.com/api/v1/messages with your API key and the model "claude-sonnet-5-5", using the anthropic-compatible request format shown in the quick start above.

What happens if a Claude Sonnet 5.5 request fails?

API Stock automatically retries the request on a reserve provider. If every provider fails, the charge is refunded to your balance.

Can I use Claude Sonnet 5.5 with the same API key as other models?

Yes. Every model on API Stock — video, image, music and chat — shares one API key and one prepaid balance, so you can switch to Claude Sonnet 5.5 without new credentials.

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