Chinese AI startup Moonshot has unveiled Kimi K3, its latest flagship AI model, claiming it is the world's first open-source model in the 3-trillion-parameter class. The launch comes as Chinese AI companies rapidly narrow the gap with leading US rivals like Anthropic and OpenAI. Moonshot said Kimi K3 delivers performance close to Anthropic's frontier Fable models while offering advanced reasoning, long-horizon coding and knowledge work capabilities. The company said the model features a 1 million-token context window, allowing it to process much larger amounts of information in a single prompt than earlier AI models.Kimi K3 AI model features 2.8 trillion parameters and 1 million-token context windowMoonshot said Kimi K3 is built with 2.8 trillion parameters, making it the largest open-source AI model released so far. The company said the model is designed for advanced coding, reasoning and enterprise knowledge work. It uses Kimi Delta Attention (KDA) and Attention Residuals, two architectural improvements aimed at handling longer inputs and deeper AI models more efficiently.Moonshot also said the model activates 16 out of 896 experts using its Stable LatentMoE framework, improving computing efficiency while reducing the resources needed to run the model.According to the company, Kimi K3 can complete long-running software engineering tasks with minimal human supervision and also combines software development with visual reasoning for tasks such as game development, frontend engineering and computer-aided design (CAD).The company said the full model weights will be released by July 27, 2026, along with a detailed technical report.Kimi K3 rivals Anthropic's Fable and other US AI modelsAccording to Reuters, Moonshot said Kimi K3 delivers performance approaching Anthropic's frontier Fable models. The company said the model "performed competitively with Fable 5 (with fallback) and substantially outperformed Opus 4.8, GPT 5.6 Sol, and GPT 5.5" in GPU kernel optimisation.The launch comes as Chinese AI firms, including Z.ai, MiniMax and DeepSeek, accelerate the release of increasingly powerful AI models. Reuters reported that the rapid pace of development is challenging the long-held view that Chinese AI companies trail their U.S. rivals by several months.Backed by investors including Alibaba and Tencent, Moonshot is also reportedly seeking $2 billion in fresh funding at a valuation of around $30 billion, according to a previous Bloomberg report.