Overview
DeepSeek V3.1, released on August 21, 2025, is DeepSeek's first model designed for the agent era. Its groundbreaking feature is hybrid inference, which allows the model to operate in two distinct modes: a standard "Non-Think" mode for efficient, general-purpose conversation, and a powerful "Think" mode for complex, multi-step reasoning. This model effectively unifies and surpasses the capabilities of DeepSeek's previous V3 (chat) and R1 (reasoning) series into a single, more efficient architecture.
Capabilities
DeepSeek V3.1's dual-mode system provides a versatile toolset for a wide range of tasks:
- Hybrid Inference: Seamlessly switch between two modes:
- Non-Think Mode: Optimized for fast, high-quality responses in general conversation, content creation, and summarization.
- Think Mode: Activates deeper reasoning pathways for complex tasks, outperforming the previous specialist R1 model in both speed and accuracy.
- Stronger Agent Skills: Enhanced post-training has significantly boosted the model's ability to use tools and execute complex, multi-step agentic workflows.
- Advanced Coding & Reasoning: Achieves superior results on difficult benchmarks like SWE-Bench and Terminal-Bench, demonstrating strong capabilities in software development and logical problem-solving.
- Open Source: The model weights are publicly available, encouraging community development and research.
Technical Specifications
DeepSeek V3.1 incorporates several key technical advancements:
- Model size: The base model was developed by continuing the pretraining of the V3 model up to 840B tokens.
- Context window: A generous 128K context window for both "Think" and "Non-Think" modes.
- Architecture: Likely a Mixture-of-Experts (MoE) Transformer for efficient scaling.
- API Endpoints: The two modes are accessed via different API endpoints:
deepseek-chatfor Non-Think mode.deepseek-reasonerfor Think mode.
Use Cases
The hybrid nature of DeepSeek V3.1 makes it suitable for a broad spectrum of applications:
- Complex Problem Solving (Think Mode): Ideal for building AI agents, performing multi-step data analysis, and tackling advanced coding challenges.
- Conversational AI (Non-Think Mode): Powering efficient and intelligent chatbots, virtual assistants, and content creation tools.
- Developer Assistance: Integrating into IDEs to provide high-quality code completion, debugging, and documentation.
- Research & Analysis: Assisting researchers by processing large documents and performing complex logical inference.
Limitations
- Mode Selection: The developer needs to consciously choose the correct mode (
chatvs.reasoner) for the task at hand to achieve optimal performance and cost-efficiency. - Knowledge Cutoff: The model's knowledge is based on its training data and does not include real-time information.
Pricing & Access
DeepSeek V3.1 is available via its API and as an open-source model:
- API Access: Pay-per-use pricing is available, with different rates for the
chatandreasonerendpoints. - Open Source: The model weights can be downloaded from Hugging Face for local or private cloud deployment.
- Web Interface: Users can test both modes on the DeepSeek Chat platform.
Ecosystem & Tools
- DeepSeek Chat: The official web interface to interact with the model.
- Hugging Face: Hub for the open-source model weights and documentation.
- DeepSeek API: The official API for programmatic access.
- Anthropic API Compatibility: Supports the Anthropic API format for easier integration into existing applications.