Claude Opus 4.5 vs Kimi K2
Anthropic Claude Opus 4.5 | Moonshot AI Kimi K2 | |
|---|---|---|
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | Nov 24 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. | 90%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. | 80.9%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. | 87%Best | 75.1% |
| Timeline | ||
| Release gap | Kimi K2 shipped 136 days before Claude Opus 4.5 | |
Which is better: Claude Opus 4.5 or Kimi K2?
Claude Opus 4.5 leads Kimi K2 on 3 of the 3 benchmarks they both report (BullshitBench v2, SWE-Bench Verified, GPQA Diamond). Kimi K2 shipped 136 days before Claude Opus 4.5, so benchmark comparisons should account for the intervening progress.
Claude Opus 4.5 is proprietary, while Kimi K2 is open weight.
On BullshitBench v2, Claude Opus 4.5 leads at 90% vs Kimi K2 at 10%. On SWE-Bench Verified, Claude Opus 4.5 leads at 80.9% vs Kimi K2 at 65.8%. On GPQA Diamond, Claude Opus 4.5 leads at 87% vs Kimi K2 at 75.1%.
Frequently asked questions
Claude Opus 4.5 was released by Anthropic on Nov 24 2025.
Kimi K2 was released by Moonshot AI on Jul 11 2025.
Claude Opus 4.5 leads on SWE-Bench Verified — Claude Opus 4.5 80.9% vs Kimi K2 65.8%.
Claude Opus 4.5 leads on GPQA Diamond — Claude Opus 4.5 87% vs Kimi K2 75.1%.
Claude Opus 4.5 is a proprietary model released by Anthropic. Kimi K2 is an open weight model released by Moonshot AI.