DeepSeek

DeepSeek is the assistant that proved frontier-adjacent quality could be delivered cheaply. Its free app is fast and genuinely capable at reasoning and coding, it shows its chain of thought, and because the underlying models are open-weight, developers can run them on their own infrastructure at very low cost.

The defining tradeoff is data. Conversations through the app are processed on servers in China under Chinese jurisdiction, and several governments have restricted it on official devices. Its writing is less polished than Claude’s and its feature set thinner than ChatGPT’s or Gemini’s. For non-sensitive work it is excellent value; for confidential material, self-hosting or another provider is wiser.