Kimi K2 vs Grok 4 Heavy
Moonshot AI Kimi K2 | SpaceXAI Grok 4 Heavy | |
|---|---|---|
| Overview | ||
| Company | Moonshot AI | SpaceXAI |
| Release date | Jul 11 2025 | Jul 9 2025 |
| Access | Open Weight | Proprietary |
| 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. | 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% | — |
| Timeline | ||
| Release gap | Grok 4 Heavy shipped 2 days before Kimi K2 | |
Which is better: Kimi K2 or Grok 4 Heavy?
Kimi K2 and Grok 4 Heavy don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Grok 4 Heavy shipped 2 days before Kimi K2, so benchmark comparisons should account for the intervening progress.
Kimi K2 is open weight, while Grok 4 Heavy is proprietary.
Direct benchmark comparisons are unavailable — Kimi K2 and Grok 4 Heavy don't publish scores on any of the same benchmarks.
Frequently asked questions
Kimi K2 was released by Moonshot AI on Jul 11 2025.
Grok 4 Heavy was released by SpaceXAI on Jul 9 2025.
Kimi K2 is an open weight model released by Moonshot AI. Grok 4 Heavy is a proprietary model released by SpaceXAI.
Other comparisons
Kimi K2 vs Claude Sonnet 5Grok 4 Heavy vs Claude Sonnet 5Kimi K2 vs GPT-5.6 SolGrok 4 Heavy vs GPT-5.6 SolKimi K2 vs Gemini OmniGrok 4 Heavy vs Gemini OmniKimi K2 vs Muse Spark 1.1Grok 4 Heavy vs Muse Spark 1.1Kimi K2 vs DeepSeek-V4-ProGrok 4 Heavy vs DeepSeek-V4-ProKimi K2 vs Mistral Medium 3.5Grok 4 Heavy vs Mistral Medium 3.5