Claude Sonnet 5
AnthropicReleased Jun 30, 2026
Sonnet 5 is Anthropic's most capable Sonnet-class model, with frontier performance across coding, agents, and professional work. It supports adaptive thinking with selectable reasoning effort levels (low, medium, high, max,...
- Context window
- 1M tokens
- Max output
- 128K tokens
- Input
- text, image, file
- Output
- text
- Tokenizer
- Claude
- Released
- Jun 30, 2026
- Reasoning
- optional
Pricing
Per 1M tokens. The provider price and our flat 3% fee are separate columns — what you pay is their sum.
| Per 1M tokens | Provider | + 3% fee | You pay |
|---|---|---|---|
| Input | $2.00 | $0.060 | $2.06 |
| Output | $10.00 | $0.300 | $10.30 |
| Cache read | $0.200 | $0.0060 | $0.206 |
| Cache write | $2.50 | $0.075 | $2.58 |
Benchmarks
Artificial Analysis
- Intelligence index
- 53.4
- Coding index
- 71.5
- Agentic index
- 46.7
Supported parameters
- include_reasoning
- max_completion_tokens
- max_tokens
- reasoning
- response_format
- stop
- structured_outputs
- tool_choice
- tools
- verbosity
Call it
OpenAI-compatible: point your SDK at api.openkey.ai/v1 and use model anthropic/claude-sonnet-5.
curl https://api.openkey.ai/v1/chat/completions \
-H "Authorization: Bearer $OPENKEY_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "anthropic/claude-sonnet-5",
"messages": [{"role": "user", "content": "Hello"}]
}'import os
from openai import OpenAI
client = OpenAI(
base_url="https://api.openkey.ai/v1",
api_key=os.environ["OPENKEY_API_KEY"],
)
completion = client.chat.completions.create(
model="anthropic/claude-sonnet-5",
messages=[{"role": "user", "content": "Hello"}],
)
print(completion.choices[0].message.content)import OpenAI from "openai";
const client = new OpenAI({
baseURL: "https://api.openkey.ai/v1",
apiKey: process.env.OPENKEY_API_KEY,
});
const completion = await client.chat.completions.create({
model: "anthropic/claude-sonnet-5",
messages: [{ role: "user", content: "Hello" }],
});
console.log(completion.choices[0].message.content);Questions
- How much does Claude Sonnet 5 cost via API?
- Through OpenKey, Claude Sonnet 5 costs $2.06 per 1M input tokens and $10.30 per 1M output tokens. That is the provider price ($2.00 / $10.00) plus a flat 3% fee — nothing else.
- What is Claude Sonnet 5's context window?
- Claude Sonnet 5 accepts up to 1M tokens of context and returns up to 128K tokens per request.
- Is Claude Sonnet 5 OpenAI-compatible?
- Yes. Send requests to OpenKey's /v1/chat/completions endpoint with model "anthropic/claude-sonnet-5" using any OpenAI SDK — only the base URL and API key change.
- What inputs does Claude Sonnet 5 support?
- Claude Sonnet 5 accepts text, image, file input and produces text output.
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