When was Claude Opus 4.1 released?

Claude Opus 4.1 was released by Anthropic on Aug 5 2025.

When was Kimi K2 released?

Kimi K2 was released by Moonshot AI on Jul 11 2025.

Which is better at coding, Claude Opus 4.1 or Kimi K2?

Claude Opus 4.1 leads on SWE-Bench Verified — Claude Opus 4.1 74.5% vs Kimi K2 65.8%.

Which scores higher on GPQA Diamond, Claude Opus 4.1 or Kimi K2?

Claude Opus 4.1 leads on GPQA Diamond — Claude Opus 4.1 80.9% vs Kimi K2 75.1%.

Is Claude Opus 4.1 or Kimi K2 open source?

Kimi K2 is an open-source / open-weight model released by Moonshot AI. Claude Opus 4.1 is a proprietary model released by Anthropic.

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Claude Opus 4.8

May 28 2026

Home/Compare/Claude Opus 4.1 vs Kimi K2

Claude Opus 4.1 vs Kimi K2

2 vs 0 benchmarks won

	Anthropic Claude Opus 4.1	Moonshot AI Kimi K2
Overview
Company	Anthropic	Moonshot AI
Release date	Aug 5 2025	Jul 11 2025
Model type	—	—
Open source	No	Yes
Specifications
Parameters	—	1T
Context window	—	128k
Benchmarks
Coding SWE-Bench Verified	74.5%Best	65.8%
Science GPQA Diamond	80.9%Best	75.1%
Timeline
Release gap	Kimi K2 shipped 25 days before Claude Opus 4.1

Which is better: Claude Opus 4.1 or Kimi K2?

Claude Opus 4.1 leads Kimi K2 on 2 of the 2 benchmarks they both report (SWE-Bench Verified, GPQA Diamond). Kimi K2 shipped 25 days before Claude Opus 4.1, so benchmark comparisons should account for the intervening progress.

Kimi K2 is an open-source / open-weight model; Claude Opus 4.1 is proprietary.

On SWE-Bench Verified, Claude Opus 4.1 leads at 74.5% vs Kimi K2 at 65.8%. On GPQA Diamond, Claude Opus 4.1 leads at 80.9% vs Kimi K2 at 75.1%.

Frequently asked questions

When was Claude Opus 4.1 released?: Claude Opus 4.1 was released by Anthropic on Aug 5 2025.
When was Kimi K2 released?: Kimi K2 was released by Moonshot AI on Jul 11 2025.
Which is better at coding, Claude Opus 4.1 or Kimi K2?: Claude Opus 4.1 leads on SWE-Bench Verified — Claude Opus 4.1 74.5% vs Kimi K2 65.8%.
Which scores higher on GPQA Diamond, Claude Opus 4.1 or Kimi K2?: Claude Opus 4.1 leads on GPQA Diamond — Claude Opus 4.1 80.9% vs Kimi K2 75.1%.
Is Claude Opus 4.1 or Kimi K2 open source?: Kimi K2 is an open-source / open-weight model released by Moonshot AI. Claude Opus 4.1 is a proprietary model released by Anthropic.