Moonshot AI Kimi K1.5 vs xAI Grok 4.1 Fast — side-by-side specs.
Moonshot AI Kimi K1.5 | xAI Grok 4.1 Fast | |
|---|---|---|
| Overview | ||
| Company | Moonshot AI | xAI |
| Release date | Jan 20 2025 | Nov 19 2025 |
| Model type | — | — |
| Open source | No | No |
| Specifications | ||
Parameters | — | — |
Context window | 128k | — |
| Benchmarks | ||
Science reasoning GPQA Diamond | — | — |
Software engineering SWE-Bench Verified | — | — |
Multimodal understanding MMMU | — | — |
| Timeline | ||
| Release gap | Kimi K1.5 shipped 303 days before Grok 4.1 Fast | |
Kimi K1.5 and Grok 4.1 Fast do not have directly comparable benchmark scores published on GPQA Diamond, SWE-Bench Verified, or MMMU. Kimi K1.5 shipped 303 days before Grok 4.1 Fast, so benchmark comparisons should account for the intervening progress.
Published specifications for these two models are limited — see each model page for the latest details.
Direct benchmark comparisons are unavailable — at least one of these models has not published scores on GPQA Diamond, SWE-Bench Verified, or MMMU.