Claude Opus 4.1

Anthropic • Messages API

claude-opus-4-1-20250805Model ID

2025-08-05Release Date

claude-opus-4-1Alias

anthropic

Claude Opus 4.1

Last checked: 2025-08-11

Model ID

claude-opus-4-1-20250805

Release2025-08-05

Aliasclaude-opus-4-1

APIMessages API

Endpoints

base_url

https://api.anthropic.com/v1

messages

/messages

Install

Node

npm i @anthropic-ai/sdk

Python

pip install anthropic

Environment

api_key

ANTHROPIC_API_KEY

Code examples

JavaScript

import Anthropic from "@anthropic-ai/sdk";\nconst anthropic = new Anthropic({ apiKey: process.env.ANTHROPIC_API_KEY });\nconst msg = await anthropic.messages.create({\n  model: "claude-opus-4-1-20250805",\n  max_tokens: 1024,\n  messages: [{ role: "user", content: "Write a 3-line haiku about sunrise over London." }]\n});\nconsole.log(msg.content[0].text);

Python

from anthropic import Anthropic\nclient = Anthropic()\nmessage = client.messages.create(\n    model="claude-opus-4-1-20250805",\n    max_tokens=1024,\n    messages=[{"role": "user", "content": "Write a 3-line haiku about sunrise over London."}]\n)\nprint(message.content[0].text)

Documentation

Anthropic – Models (shows Opus 4.1 + ids)Messages API examples (shows exact model id usage)Client SDKs

Notes

Use the snapshot id (claude-opus-4-1-YYYYMMDD) for strict reproducibility or the alias claude-opus-4-1 to track the latest.