Anthropic/v1/ai/anthropic/claude-sonnet-4

Claude Sonnet 4

Access Claude Sonnet 4 through one API key. Anthropic's best balance of speed and intelligence.

Anthropic's balanced model. Excellent at writing, analysis, coding, and complex multi-step tasks with a massive context window.

Full Docs Get API Key

Context Window

200K tokens

Max Output

8K tokens

Input Price

$3.00 / 1M tokens

Output Price

$15.00 / 1M tokens

Try it live

Send a message and see Claude Sonnet 4 respond in real time.

POST /v1/ai/anthropic/claude-sonnet-4Live testing

API Key

Message *

Max Tokens

Maximum tokens in the response.

Stream

Real-time token streaming

Hit "Run" to see the response

Strengths

✓Excellent writing

✓Complex analysis

✓Code generation

✓200K context window

Quick start

Copy this snippet and start making calls with Claude Sonnet 4.

const res = await fetch('https://api.yepapi.com/v1/ai/anthropic/claude-sonnet-4', {
  method: 'POST',
  headers: {
    'x-api-key': 'YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    "messages": [
      {
        "role": "user",
        "content": "Explain API gateways in 2 sentences."
      }
    ],
    "maxTokens": 256
  }),
});
const data = await res.json();
console.log(data);

Why use Claude Sonnet 4 through YepAPI?

✓One API key for all models — no separate accounts

✓OpenAI SDK compatible — just change the base URL

✓No monthly minimums — pay per token

✓Switch models with one line of code

✓Full provider passthrough — citations, search results, and all extras included

✓Streaming and non-streaming support on every model

✓Works with Cursor, Claude, LangChain, and any LLM tool

✓Unified billing across all providers

Frequently asked questions

Anthropic's balanced model. Excellent at writing, analysis, coding, and complex multi-step tasks with a massive context window.

Input tokens cost $3.00 per 1M tokens and output tokens cost $15.00 per 1M tokens through YepAPI. No monthly minimums — you only pay for what you use.

Sign up for a free API key, then send requests to the /v1/ai/anthropic/claude-sonnet-4 endpoint. YepAPI is OpenAI SDK compatible, so you can use it with any tool that supports OpenAI — just change the base URL.

Claude Sonnet 4 supports a 200K token context window with up to 8K output tokens per request.