DeepSeek-V3.1 is a state-of-the-art hybrid AI model featuring 685 billion parameters and a 128,000-token context window. It integrates chat, advanced reasoning, and coding capabilities in a single system, supporting both 'thinking' (chain-of-thought) and 'non-thinking' (direct answer) modes. The model is built on a Mixture-of-Experts architecture, activating only a subset of parameters per token for efficient inference. DeepSeek-V3.1 excels at tool calling, agentic workflows, and multilingual tasks, making it suitable for complex problem-solving, coding, and enterprise applications. It is available via chat interface, API, and open-source weights, and is released under the MIT license for commercial use and modification.