Quick Answer
Kimi K3 is a frontier-class, open-source large language model built by Moonshot AI (月之暗面). Released in July 2026, it packs 2.8 trillion parameters, a 1-million-token context window, and a novel hybrid architecture combining linear and full attention mechanisms. It is the first open-source model to beat Claude and GPT in frontend coding benchmarks, and it costs significantly less per solved task. This guide covers everything you need to know: what K3 is, how it works under the hood, how it compares to the competition, and how to start using it today.
What Is Kimi K3?
Kimi K3 is the third generation of Moonshot AI's flagship model family, succeeding the well-regarded Kimi K2 and K2.5. Unlike many Chinese AI models that prioritize benchmark scores over real-world usability, K3 was designed from the ground up for long-horizon agentic tasks — the kind where an AI codes a full feature, navigates a large codebase, or maintains coherent reasoning across hundreds of thousands of tokens.
Moonshot AI announced K3 on July 16, 2026, and released the open weights on July 27, 2026 — a deliberate five-day gap that let the inference ecosystem (vLLM, NVIDIA, AMD) prepare day-zero support. The model is available through the Kimi web app, the Kimi API, the Kimi Code terminal agent, and third-party API gateways.
