Compare AI models
| Specifications | ||
ParametersA rough measure of how big the model is. More parameters usually means more capable and more expensive to run, though it is a poor guide on its own — a smaller, newer model often beats a larger, older one. | — | 1T |
Context windowHow much text the model can hold in mind at once — your question, any documents you attach, the conversation so far, and its own reply. Go past it and the earliest part falls out of view. | — | 128k |
| API pricingUSD per 1M tokens · lower wins | ||
Cheapest inputLowest input rate across every provider on OpenRouter, the lab included. The cheapest endpoint may run a quantised build or a shorter context — see "Available from" on the model page. | $15.00Amazon Bedrock | $0.57Novita |
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input. | $75.00Amazon Bedrock | $2.30Novita |
| $6,750Amazon Bedrock | $229Novita · fp8 | |
| Benchmarks | ||
BullshitBench v2Nonsense detection — Given 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. | 43% | 10% |
SWE-Bench VerifiedCoding — Real 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. | 74.5% | 65.8% |
GPQA DiamondScience — Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 80.9% | 75.1% |
Humanity's Last Exam · with toolsMultidisciplinary reasoning — Humanity's Last Exam — extremely hard expert questions across many subjects. “With tools” means the AI is allowed to search the web or run code while answering. Higher is better. | — | 4.7% |
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | Aug 5 2025 | Jul 11 2025 |
| Access | Closed | Open Weight |
| Model details | View model | View model |
Other comparisons
Claude Opus 4.1vsGPT-6.1 SolKimi K2vsGPT-6.1 SolClaude Opus 4.1vsGemini 4 ArgonKimi K2vsGemini 4 ArgonClaude Opus 4.1vsMuse WonderKimi K2vsMuse WonderClaude Opus 4.1vsGrok 4.7Kimi K2vsGrok 4.7Claude Opus 4.1vsDeepSeek-V4.1-FlashKimi K2vsDeepSeek-V4.1-FlashClaude Opus 4.1vsMistral Large 4Kimi K2vsMistral Large 4Frequently asked questions
Claude Opus 4.1 leads Kimi K2 on 3 of the 3 benchmarks they both report (BullshitBench v2, SWE-Bench Verified, GPQA Diamond). Kimi K2 shipped 25 days before Claude Opus 4.1, so benchmark comparisons should account for the intervening progress.
Claude Opus 4.1 is closed, while Kimi K2 is open weight.
On BullshitBench v2, Claude Opus 4.1 leads at 43% vs Kimi K2 at 10%. On SWE-Bench Verified, Claude Opus 4.1 leads at 74.5% vs Kimi K2 at 65.8%. On GPQA Diamond, Claude Opus 4.1 leads at 80.9% vs Kimi K2 at 75.1%.