Anthropic: Claude Opus 4.1 API
Claude Opus 4.1 is a targeted performance upgrade to Anthropic's flagship Opus 4 series. Serving as a drop-in replacement, it maintains the same API footprint and pricing while delivering substantial gains in real-world software engineering and long-horizon agentic workflows. Scoring 74.5% on SWE-bench Verified, it outperforms the original Opus 4 by providing superior multi-file refactoring and pinpoint error-tracking capabilities. It features a "hybrid reasoning" architecture that allows developers to toggle between near-instant responses and deep "Extended Thinking" modes. This makes it an industry leader for autonomous coding agents, enterprise-level knowledge assistants, and complex research-level synthesis.
- Context window: 200,000 tokens
- Max output: 32,000 tokens
- Input: text, image
- Output: text
- Reasoning: Supported
- Tool calling: Supported
- File input: Supported
- Released: 2025-08-05
- Knowledge cutoff: 2025-04-30
Frequently Asked Questions
What is the context window of Claude Opus 4.1?
Claude Opus 4.1 supports a context window of up to 200,000 tokens.
Does Claude Opus 4.1 support function calling?
Yes. Claude Opus 4.1 supports tool / function calling.
Does Claude Opus 4.1 support reasoning?
Yes. Claude Opus 4.1 is a reasoning-capable model.
What is the knowledge cutoff of Claude Opus 4.1?
The knowledge cutoff of Claude Opus 4.1 is 2025-04-30.