Claude Sonnet 4 vs Kimi K2
Anthropic Claude Sonnet 4 | Moonshot AI Kimi K2 | |
|---|---|---|
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | May 22 2025 | 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. | 30%Best | 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. | 72.7%Best | 65.8% |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 75.4%Best | 75.1% |
| Timeline | ||
| Release gap | Claude Sonnet 4 shipped 50 days before Kimi K2 | |
Which is better: Claude Sonnet 4 or Kimi K2?
Claude Sonnet 4 leads Kimi K2 on 3 of the 3 benchmarks they both report (BullshitBench v2, SWE-Bench Verified, GPQA Diamond). Claude Sonnet 4 shipped 50 days before Kimi K2, so benchmark comparisons should account for the intervening progress.
Claude Sonnet 4 is proprietary, while Kimi K2 is open weight.
On BullshitBench v2, Claude Sonnet 4 leads at 30% vs Kimi K2 at 10%. On SWE-Bench Verified, Claude Sonnet 4 leads at 72.7% vs Kimi K2 at 65.8%. On GPQA Diamond, Claude Sonnet 4 leads at 75.4% vs Kimi K2 at 75.1%.
Frequently asked questions
Claude Sonnet 4 was released by Anthropic on May 22 2025.
Kimi K2 was released by Moonshot AI on Jul 11 2025.
Claude Sonnet 4 leads on SWE-Bench Verified — Claude Sonnet 4 72.7% vs Kimi K2 65.8%.
Claude Sonnet 4 leads on GPQA Diamond — Claude Sonnet 4 75.4% vs Kimi K2 75.1%.
Claude Sonnet 4 is a proprietary model released by Anthropic. Kimi K2 is an open weight model released by Moonshot AI.