Claude Sonnet 4.5 API
Anthropic’s models for code, writing and agents. Haiku is fast and cheap, Sonnet is the everyday workhorse, Opus and Fable take the hardest tasks. The natural pick for Claude Code.
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Anthropic’s models for code, writing and agents. Haiku is fast and cheap, Sonnet is the everyday workhorse, Opus and Fable take the hardest tasks. The natural pick for Claude Code.
| Model ID | claude-sonnet-4-5 |
| Vendor | Anthropic |
| Family | Claude |
| Balance rate | ×1.5 / ×7.5 |
| Cache read | $0.03 per 1M tokens |
Both API formats
The model answers in the Anthropic Messages format and in the OpenAI Chat Completions format. Only the address and the key change.
curl https://api.klinch.cloud/v1/messages \
-H "x-api-key: kl_live_…" \
-H "content-type: application/json" \
-d '{"model": "claude-sonnet-4-5", "max_tokens": 1024,
"messages": [{"role": "user", "content": "Hello"}]}'from openai import OpenAI
client = OpenAI(base_url="https://api.klinch.cloud/v1", api_key="kl_live_…")
r = client.chat.completions.create(
model="claude-sonnet-4-5",
messages=[{"role": "user", "content": "Hello"}],
)
print(r.choices[0].message.content)FAQ
How much does Claude Sonnet 4.5 cost on KLINCH?
$0.3 per 1M input tokens and $1.5 per 1M output tokens. Anthropic’s list price is $3 and $15. The balance is charged ×1.5 per input and ×7.5 per output token.
How do I call Claude Sonnet 4.5 through the API?
Use the KLINCH API address, your kl_live_… key and the model claude-sonnet-4-5. The Anthropic SDK, the OpenAI SDK, Claude Code, Cursor and any client with a custom base URL work.
Is there a subscription?
No. You buy a token pack once and tokens are charged as you use them.
Is this the official Anthropic API?
No. KLINCH is not affiliated with Anthropic. We provide access to the model through our own gateway that speaks the Anthropic and OpenAI APIs.
One key, one balance, every top model
Claude, GPT, Gemini, DeepSeek and Grok at a tenth of the official price. No subscription, pay as you go.