Claude 3.5 Sonnet (upgraded) vs Kimi K2 (0905)
Anthropic Claude 3.5 Sonnet (upgraded) | Moonshot AI Kimi K2 (0905) | |
|---|---|---|
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | Oct 22 2024 | Sep 5 2025 |
| Access | Proprietary | Open Weight |
| Specifications | ||
Parameters | — | 1T |
Context window | — | 256k |
| Benchmarks | ||
Coding SWE-Bench VerifiedReal coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 49% | 65.8%Best |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | — | 75.1% |
| Timeline | ||
| Release gap | Claude 3.5 Sonnet (upgraded) shipped 318 days before Kimi K2 (0905) | |
Which is better: Claude 3.5 Sonnet (upgraded) or Kimi K2 (0905)?
Kimi K2 (0905) leads Claude 3.5 Sonnet (upgraded) on 1 of the 1 benchmark they both report (SWE-Bench Verified). Claude 3.5 Sonnet (upgraded) shipped 318 days before Kimi K2 (0905), so benchmark comparisons should account for the intervening progress.
Claude 3.5 Sonnet (upgraded) is proprietary, while Kimi K2 (0905) is open weight.
On SWE-Bench Verified, Kimi K2 (0905) leads at 65.8% vs Claude 3.5 Sonnet (upgraded) at 49%.
Frequently asked questions
Claude 3.5 Sonnet (upgraded) was released by Anthropic on Oct 22 2024.
Kimi K2 (0905) was released by Moonshot AI on Sep 5 2025.
Kimi K2 (0905) leads on SWE-Bench Verified — Claude 3.5 Sonnet (upgraded) 49% vs Kimi K2 (0905) 65.8%.
Claude 3.5 Sonnet (upgraded) is a proprietary model released by Anthropic. Kimi K2 (0905) is an open weight model released by Moonshot AI.