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. | — | 256k |
| 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. | — | $0.60Novita |
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input. | — | $2.50Novita |
| — | $245Novita · fp8 | |
| Benchmarks | ||
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. | 72.5% | 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. | 79.6% | 75.1% |
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. | 34% | — |
| Overview | ||
| Company | Anthropic | Moonshot AI |
| Release date | May 22 2025 | Sep 5 2025 |
| Access | Closed | Open Weight |
| Model details | View model | View model |
Other comparisons
Claude Opus 4vsGPT-6.1 SolKimi K2 (0905)vsGPT-6.1 SolClaude Opus 4vsGemini 4 ArgonKimi K2 (0905)vsGemini 4 ArgonClaude Opus 4vsMuse WonderKimi K2 (0905)vsMuse WonderClaude Opus 4vsGrok 4.7Kimi K2 (0905)vsGrok 4.7Claude Opus 4vsDeepSeek-V4.1-FlashKimi K2 (0905)vsDeepSeek-V4.1-FlashClaude Opus 4vsMistral Large 4Kimi K2 (0905)vsMistral Large 4Frequently asked questions
Claude Opus 4 leads Kimi K2 (0905) on 2 of the 2 benchmarks they both report (SWE-Bench Verified, GPQA Diamond). Claude Opus 4 shipped 106 days before Kimi K2 (0905), so benchmark comparisons should account for the intervening progress.
Claude Opus 4 is closed, while Kimi K2 (0905) is open weight.
On SWE-Bench Verified, Claude Opus 4 leads at 72.5% vs Kimi K2 (0905) at 65.8%. On GPQA Diamond, Claude Opus 4 leads at 79.6% vs Kimi K2 (0905) at 75.1%.