Claude 3.5 Sonnet (upgraded)vsKimi K2 (0905)
Claude 3.5 Sonnet (upgraded) | Kimi K2 (0905) | |
|---|---|---|
| Specifications | ||
ParametersA rough measure of how big the model is. More parameters usually means more capable and more expensive to run, though it is a poor guide on its own — a smaller, newer model often beats a larger, older one. | — | 1T |
Context windowHow much text the model can hold in mind at once — your question, any documents you attach, the conversation so far, and its own reply. Go past it and the earliest part falls out of view. | — | 256k |
| Benchmarks | ||
SWE-Bench VerifiedCoding — Real 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% |
| BenchmarksPublished by one model only | ||
GPQA DiamondScience — Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | — | 75.1% |
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | Oct 22 2024 | Sep 5 2025 |
| Access | Proprietary | Open Weight |
Frequently asked questions
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%.
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.