DeepSeek

A Chinese AI lab that released DeepSeek-R1 in January 2025, a 671B-parameter open-weight reasoning model achieving performance comparable to OpenAI's o1 at significantly lower cost. DeepSeek-R1 generates visible chain-of-thought reasoning using GRPO training and demonstrated that pure RL with verifiable rewards can produce emergent reasoning. DeepSeek-V3 uses a MoE architecture with ~37B active parameters.