DeepSeek V3.1 represents a significant advancement in open-source large language models (LLMs), introducing hybrid reasoning modes that allow users to switch between "thinking" (chain-of-thought) and "non-thinking" (rapid reply) modes, effectively reducing hallucinations by 38% compared to its predecessor. This version is optimized for real-world applications with enhanced tool integration, expanded multilingual capabilities covering over 100 languages, and an architecture that supports massive context capacity, making it suitable for complex tasks such as agentic workflows and long-document analysis. With its Sparse Mixture-of-Experts architecture and ~685 billion parameters, DeepSeek V3.1 offers improved performance, especially in multi-step reasoning tasks and maintaining coherence across contexts. It is designed for a range of impactful applications, including smart research copilots, enterprise agent workflows, code companions, and global conversational assistants, making it a powerful tool for teams developing high-complexity AI applications in diverse linguistic environments.