2 vs 0 benchmarks won
Anthropic Claude Opus 4.1 | Moonshot AI Kimi K2 (0905) | |
|---|---|---|
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | Aug 5 2025 | Sep 5 2025 |
| Model type | — | — |
| Open source | No | Yes |
| Specifications | ||
Parameters | — | 1T |
Context window | — | 256k |
| Benchmarks | ||
Science reasoning GPQA Diamond | 80.9% | 75.1% |
Software engineering SWE-Bench Verified | 74.5% | 65.8% |
Multimodal understanding MMMU | — | — |
| Timeline | ||
| Release gap | Claude Opus 4.1 shipped 31 days before Kimi K2 (0905) | |
Claude Opus 4.1 leads Kimi K2 (0905) on 2 of the tracked benchmarks (GPQA Diamond, SWE-Bench Verified, MMMU). Claude Opus 4.1 shipped 31 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 4.1 is proprietary.
On GPQA Diamond, Claude Opus 4.1 scores 80.9%, 5.8 points above Kimi K2 (0905) at 75.1%. On SWE-Bench Verified, Claude Opus 4.1 scores 74.5%, 8.7 points above Kimi K2 (0905) at 65.8%.