Kimi K2vsGrok 4.1 Fast
Kimi K2 | Grok 4.1 Fast | |
|---|---|---|
| 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% | 19%Best |
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. | 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. | 75.1% | — |
| Overview | ||
| Company | Moonshot AI | SpaceXAI |
| Release date | Jul 11 2025 | Nov 19 2025 |
| Access | Open Weight | Proprietary |
Which is better: Kimi K2 or Grok 4.1 Fast?
Grok 4.1 Fast leads Kimi K2 on 1 of the 1 benchmark they both report (BullshitBench v2). Kimi K2 shipped 131 days before Grok 4.1 Fast, so benchmark comparisons should account for the intervening progress.
Kimi K2 is open weight, while Grok 4.1 Fast is proprietary.
On BullshitBench v2, Grok 4.1 Fast leads at 19% vs Kimi K2 at 10%.
Frequently asked questions
Kimi K2 was released by Moonshot AI on Jul 11 2025.
Grok 4.1 Fast was released by SpaceXAI on Nov 19 2025.
Kimi K2 is an open weight model released by Moonshot AI. Grok 4.1 Fast is a proprietary model released by SpaceXAI.
Other comparisons
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