Claude Sonnet 4 API

anthropic/claude-sonnet-4
Claude Sonnet 4 is Anthropic's balanced, mid-size model with strong coding and reasoning capabilities.
Context
1M tokens
Input
$4.1262 / 1M tokens
Output
$20.631 / 1M tokens
Released
May 22, 2025

How to use Claude Sonnet 4 API

Install any OpenAI-compatible SDK, point it at api.aimlapi.com/v1, and set the model to anthropic/claude-sonnet-4.
import requests

r = requests.post(
    "https://api.aimlapi.com/v1/chat/completions",
    headers={"Authorization": "Bearer " + AIMLAPI_KEY},
    json={
      "model": "anthropic/claude-sonnet-4",
      "messages": [
        {
          "role": "user",
          "content": "Hello!"
        }
      ]
    },
)
print(r.json())
const r = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "anthropic/claude-sonnet-4",
    "messages": [
      {
        "role": "user",
        "content": "Hello!"
      }
    ]
  }),
});
console.log(await r.json());
curl -X POST https://api.aimlapi.com/v1/chat/completions \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"anthropic/claude-sonnet-4","messages":[{"role":"user","content":"Hello!"}]}'

OpenAI-compatible — swap the base URL and it works with your existing SDK.

Claude Sonnet 4 API Pricing

TypePrice
Input
$4.1262 / 1M tokens
Output
$20.631 / 1M tokens
Cached input
$0.41262 / 1M tokens

Claude Sonnet 4 documents cache write tokens as billed at 1.25× the base input price for 5-minute caching and 2× for 1-hour caching.

Claude Sonnet 4 Benchmarks

BenchmarkScoreWhat it measuresSourceRetrieved
Intelligence
18.9
Composite score across standardised reasoning, knowledge and problem-solving evaluations, measured independently by Artificial AnalysisSourceSeptember 22, 2026
Coding
37.6
Composite score across standardised coding evaluations, measured independently by Artificial AnalysisSourceSeptember 22, 2026
Math
74.3
Composite score across standardised mathematics evaluations, measured independently by Artificial AnalysisSourceSeptember 22, 2026

Claude Sonnet 4 vs other models

ModelInputOutputContextBest for
$4.1262 / 1M tokens
$20.631 / 1M tokens
1M tokens
Agentic workflows and structured output
$6.5 / 1M tokens
$32.5 / 1M tokens
1M tokens
Complex agentic coding and enterprise workflows
$6.5 / 1M tokens
$32.5 / 1M tokens
1M tokens
Chat + assistants
$13 / 1M tokens
$65 / 1M tokens
1M tokens
Chat + assistants

Frequently asked questions

Claude Sonnet 4 has a 1,000,000 tokens context window and can return up to 64,000 tokens.

Claude Sonnet 4 takes image, text as input and returns text.

Use anthropic/claude-sonnet-4 as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.

Claude Sonnet 4 became available on May 22, 2025.

Claude Sonnet 4 is priced at input $4.1262 / 1M tokens, output $20.631 / 1M tokens, cached input $0.41262 / 1M tokens.

Yes, Claude Sonnet 4 can stream responses as they are generated.

Yes, Claude Sonnet 4 accepts image input alongside text.

Claude Sonnet 4 was built by Anthropic.

Yes, Claude Sonnet 4 accepts image and text input alongside text output, and supports vision as a listed capability.

Yes, it supports tool use, including parallel tool calls.

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