DeepSeek is a Chinese AI lab that releases open-weight models alongside a free chat app and one of the cheapest developer APIs available. It competes with frontier models on coding and reasoning while costing a fraction to run at scale, and the weights are open so you can self-host.
Use the fast model for cheap, high-volume work and the pro model for the hardest reasoning and coding. Reuse a common prompt prefix so repeated calls hit the cache and cut input cost sharply. You can invoke a thinking mode for problems that need visible step-by-step work.
Cost-sensitive, high-volume API work. Coding and step-by-step reasoning. Self-hosting, since the model weights are openly released.
Very large context with long output limits, plus a thinking mode that shows its reasoning. As a China-based model it restricts some politically sensitive topics. Weights are open, so you can self-host instead of using the hosted API.
Reuse a fixed system prefix to trigger cache-hit pricing. Pick the flash model for volume, the pro model for hard problems. Expect content limits on politically sensitive topics.
Free consumer chat app. The API is usage-based and among the lowest priced of any frontier-class model, with a large discount for cached input.
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