DeepSeek V4.1 Flash

A smaller cache is an architectural choice

The model card lists 552 billion backbone parameters. It activates 8 billion per token during prefill and 16 billion during decode. The decoder’s global key-value cache is projected from final encoder states, rather than built independently at every decoder layer.DeepSeek V4.1 Flash model card

Practical guidance. The distinction matters when comparing hardware estimates. Total stored weights, active computation and attention-cache memory are separate quantities. An active-parameter figure alone is not a GPU memory requirement.

Check the actual API capabilities

The model-capability response lists image input for Flash. The Responses API supports function tools, but its built-in web_search option is ignored for Flash.DeepSeek model capability responseDeepSeek Responses API support

Practical guidance. If an application needs browsing, confirm that your own search tool ran and returned evidence. Do not infer web access from the fact that the endpoint accepts a tools field.

Include the time of day in cost estimates

Peak periods are 01:00–04:00 and 06:00–10:00 UTC on weekdays, excluding Chinese public holidays. Other periods use off-peak rates.DeepSeek models and prices

Practical guidance. Record request times when comparing your bill with an estimate. A workload moved to a different hour can change cost even when its token count stays the same.

The API follows the updated release

The first V4.1 Flash release preceded the October 1017 update. The current API alias serves 1017, while both weight releases have their own repository identifiers. A fixed local checkpoint and the moving API alias can therefore refer to different revisions.DeepSeek dated release historyDeepSeek V4.1 Flash 1017 release card