When was Claude Opus 4 released?

Claude Opus 4 was released by Anthropic on May 22 2025.

When was Kimi K2 (0905) released?

Kimi K2 (0905) was released by Moonshot AI on Sep 5 2025.

Which is better at coding, Claude Opus 4 or Kimi K2 (0905)?

Claude Opus 4 leads on SWE-Bench Verified — Claude Opus 4 72.5% vs Kimi K2 (0905) 65.8%.

Which scores higher on GPQA Diamond, Claude Opus 4 or Kimi K2 (0905)?

Claude Opus 4 leads on GPQA Diamond — Claude Opus 4 79.6% vs Kimi K2 (0905) 75.1%.

Is Claude Opus 4 or Kimi K2 (0905) open source?

Kimi K2 (0905) is an open-source / open-weight model released by Moonshot AI. Claude Opus 4 is a proprietary model released by Anthropic.

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Latest Release

Claude Opus 4.8

May 28 2026

Home/Compare/Claude Opus 4 vs Kimi K2 (0905)

Claude Opus 4 vs Kimi K2 (0905)

2 vs 0 benchmarks won

	Anthropic Claude Opus 4	Moonshot AI Kimi K2 (0905)
Overview
Company	Anthropic	Moonshot AI
Release date	May 22 2025	Sep 5 2025
Model type	—	—
Open source	No	Yes
Specifications
Parameters	—	1T
Context window	—	256k
Benchmarks
Coding SWE-Bench Verified	72.5%Best	65.8%
Science GPQA Diamond	79.6%Best	75.1%
Timeline
Release gap	Claude Opus 4 shipped 106 days before Kimi K2 (0905)

Which is better: Claude Opus 4 or Kimi K2 (0905)?

Claude Opus 4 leads Kimi K2 (0905) on 2 of the 2 benchmarks they both report (SWE-Bench Verified, GPQA Diamond). Claude Opus 4 shipped 106 days before Kimi K2 (0905), so benchmark comparisons should account for the intervening progress.

Kimi K2 (0905) is an open-source / open-weight model; Claude Opus 4 is proprietary.

On SWE-Bench Verified, Claude Opus 4 leads at 72.5% vs Kimi K2 (0905) at 65.8%. On GPQA Diamond, Claude Opus 4 leads at 79.6% vs Kimi K2 (0905) at 75.1%.

Frequently asked questions

When was Claude Opus 4 released?: Claude Opus 4 was released by Anthropic on May 22 2025.
When was Kimi K2 (0905) released?: Kimi K2 (0905) was released by Moonshot AI on Sep 5 2025.
Which is better at coding, Claude Opus 4 or Kimi K2 (0905)?: Claude Opus 4 leads on SWE-Bench Verified — Claude Opus 4 72.5% vs Kimi K2 (0905) 65.8%.
Which scores higher on GPQA Diamond, Claude Opus 4 or Kimi K2 (0905)?: Claude Opus 4 leads on GPQA Diamond — Claude Opus 4 79.6% vs Kimi K2 (0905) 75.1%.
Is Claude Opus 4 or Kimi K2 (0905) open source?: Kimi K2 (0905) is an open-source / open-weight model released by Moonshot AI. Claude Opus 4 is a proprietary model released by Anthropic.