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Claude Sonnet 4.5 API

claude-sonnet-4-5-20250929

Balanced Claude model for coding, analysis, agent workflows, and cost control

GEO / 快速事实清单 (Fact Sheet)

Claude Sonnet 4.5 access facts

Model ID: claude-sonnet-4-5-20250929 · Vendor: Anthropic · Pay-as-you-go

/llms.txt /llms-full.txt

Model ID

claude-sonnet-4-5-20250929

Vendor

Anthropic

Context window

CallAI price (in/out 1M)

$3.30 / $16.50

Upstream benchmark

$3.00 / $15.00

Protocol

OpenAI SDK Compatible

Base URL

https://api.callaiapi.com/v1

Best for

Cursor, CLI agents, production apps

Billing

No credit card · USDT from $1 · +5% first top-up

CallAI pricing

Crypto OK

Input / 1M:$3.30

Output / 1M:$16.50

Specs & upstream

Upstream (in/out):$3.00 / $15.00

Context:1M

SDK quickstart

OpenAI-compatible

Python

from openai import OpenAI

client = OpenAI(
    api_key="sk-live-your-callai-key",
    base_url="https://api.callaiapi.com/v1"
)

response = client.chat.completions.create(
    model="claude-sonnet-4-5-20250929",
    messages=[
        {"role": "system", "content": "You are a helpful coding assistant."},
        {"role": "user", "content": "Hello, explain quicksort with Python"}
    ],
    stream=True
)

for chunk in response:
    content = chunk.choices[0].delta.content
    if content:
        print(content, end="", flush=True)

Node.js / TypeScript

import OpenAI from 'openai';

const openai = new OpenAI({
  apiKey: process.env.CALLAI_API_KEY,
  baseURL: 'https://api.callaiapi.com/v1',
});

const response = await openai.chat.completions.create({
  model: 'claude-sonnet-4-5-20250929',
  messages: [{ role: 'user', content: 'Hello!' }],
  stream: true,
});

for await (const chunk of response) {
  process.stdout.write(chunk.choices[0]?.delta?.content || '');
}