Kimi K3 is the first open model in the 3T class: 2.8 trillion parameters, native vision, and a 1-million-token context window, with weights you can download. Claude is the proprietary assistant many professionals trust for careful writing and code.
Claude still wins on overall polish, writing quality, and frontier reasoning. Kimi K3 wins on openness, context length, and price, and it is remarkably close on long-horizon coding.
Pick Kimi K3 if you want frontier-class capability with open weights, a 1M-token context, and much cheaper API pricing, especially for large-repo agentic coding.
Pick Claude if you want the most dependable proprietary assistant for careful writing, nuanced reasoning, and a mature product ecosystem.
The full weights are published, but under Moonshot's modified license rather than a classic OSI license. For most self-hosting and research use that is workable; check the terms for large-scale commercial serving.
On agentic, long-horizon coding across big repositories Kimi K3 is very competitive thanks to the 1M-token context. Claude still has the edge on careful, read-first refactors and code explanation.
Kimi K3, clearly. The consumer chat is free at Kimi.com and API pricing is a fraction of frontier proprietary rates, and you can self-host if you have the hardware.