Claude 3.5 Sonnet (upgraded) vs Kimi K2
Anthropic Claude 3.5 Sonnet (upgraded) | Moonshot AI Kimi K2 | |
|---|---|---|
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | Oct 22 2024 | Jul 11 2025 |
| Access | Proprietary | Open Weight |
| Specifications | ||
Parameters | — | 1T |
Context window | — | 128k |
| Benchmarks | ||
Nonsense detection BullshitBench v2Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better. | — | 10% |
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 262 days before Kimi K2 | |
Which is better: Claude 3.5 Sonnet (upgraded) or Kimi K2?
Kimi K2 leads Claude 3.5 Sonnet (upgraded) on 1 of the 1 benchmark they both report (SWE-Bench Verified). Claude 3.5 Sonnet (upgraded) shipped 262 days before Kimi K2, so benchmark comparisons should account for the intervening progress.
Claude 3.5 Sonnet (upgraded) is proprietary, while Kimi K2 is open weight.
On SWE-Bench Verified, Kimi K2 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 was released by Moonshot AI on Jul 11 2025.
Kimi K2 leads on SWE-Bench Verified — Claude 3.5 Sonnet (upgraded) 49% vs Kimi K2 65.8%.
Claude 3.5 Sonnet (upgraded) is a proprietary model released by Anthropic. Kimi K2 is an open weight model released by Moonshot AI.
Other comparisons
Claude 3.5 Sonnet (upgraded) vs GPT-5.6 SolKimi K2 vs GPT-5.6 SolClaude 3.5 Sonnet (upgraded) vs Gemini OmniKimi K2 vs Gemini OmniClaude 3.5 Sonnet (upgraded) vs Muse Spark 1.1Kimi K2 vs Muse Spark 1.1Claude 3.5 Sonnet (upgraded) vs Grok 4.5Kimi K2 vs Grok 4.5Claude 3.5 Sonnet (upgraded) vs DeepSeek-V4-ProKimi K2 vs DeepSeek-V4-ProClaude 3.5 Sonnet (upgraded) vs Mistral Medium 3.5Kimi K2 vs Mistral Medium 3.5