DeepSeek (from China) disrupted the market in late 2024/2025 by releasing DeepSeek-V3 and R1 (Reasoning) with performance matching Claude/GPT-4 at 1/10th the cost.
When to Use
Cost Efficiency: The API is incredibly cheap.
Reasoning: DeepSeek-R1 uses Chain-of-Thought reinforcement learning (like OpenAI o1) but is open weights.
Coding: DeepSeek-Coder-V2 is a top-tier coding model.