Claude 4.5 Sonnet API

anthropic/claude-sonnet-4.5
Claude 4.
Context
200K tokens
Input
$4.1262 / 1M tokens
Output
$20.631 / 1M tokens
Released
Oct 1, 2025

How to use Claude 4.5 Sonnet API

Install any OpenAI-compatible SDK, point it at api.aimlapi.com/v1, and set the model to anthropic/claude-sonnet-4.5.
import requests

r = requests.post(
    "https://api.aimlapi.com/v1/chat/completions",
    headers={"Authorization": "Bearer " + AIMLAPI_KEY},
    json={
      "model": "anthropic/claude-sonnet-4.5",
      "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-4.5",
    "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-4.5","messages":[{"role":"user","content":"Hello!"}]}'

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

Claude 4.5 Sonnet API Pricing

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

Claude 4.5 Sonnet Benchmarks

BenchmarkScoreWhat it measuresSourceRetrieved
GPQA Diamond
83.4%
Google-proof graduate science questions (hardest subset)SourceJuly 8, 2026
OSWorld
61.4%
Computer-use across real desktop applicationsSourceJuly 8, 2026
SWE-bench Verified
77.2%
Resolving verified real GitHub issuesSourceJuly 8, 2026
Intelligence
21.2
Composite score across standardised reasoning, knowledge and problem-solving evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026
Coding
52.1
Composite score across standardised coding evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026
Math
88
Composite score across standardised mathematics evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026

Frequently asked questions

Claude 4.5 Sonnet has a 200,000 tokens context window and can return up to 64,000 tokens.

Claude 4.5 Sonnet takes text as input and returns text.

Use anthropic/claude-sonnet-4.5 as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.

Claude 4.5 Sonnet is priced at input $4.1262 / 1M tokens, output $20.631 / 1M tokens, cached input $0.41262 / 1M tokens.

Yes, Claude 4.5 Sonnet can stream responses as they are generated.

Claude 4.5 Sonnet was built by Anthropic.

Start building with Claude 4.5 Sonnet

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