Kimi K2 vs o4-mini
Moonshot AI Kimi K2 | OpenAI o4-mini | |
|---|---|---|
| Overview | ||
| Company | Moonshot AI | OpenAI |
| Release date | Jul 11 2025 | Apr 16 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%Best | 8% |
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 | o4-mini shipped 86 days before Kimi K2 | |
Which is better: Kimi K2 or o4-mini?
Kimi K2 leads o4-mini on 1 of the 1 benchmark they both report (BullshitBench v2). o4-mini shipped 86 days before Kimi K2, so benchmark comparisons should account for the intervening progress.
Kimi K2 is open weight, while o4-mini is proprietary.
On BullshitBench v2, Kimi K2 leads at 10% vs o4-mini at 8%.
Frequently asked questions
Kimi K2 was released by Moonshot AI on Jul 11 2025.
o4-mini was released by OpenAI on Apr 16 2025.
Kimi K2 is an open weight model released by Moonshot AI. o4-mini is a proprietary model released by OpenAI.