DeepSeek V4.1 Flash (1017)

Overview. DeepSeek-V4.1-Flash-1017 is a refresh of the DeepSeek V4.1 Flash weights, published by DeepSeek on 17 October 2026. It takes text and image input and produces text, over a context window of up to 1,048,576 tokens. The architecture is a sparse mixture of experts with 384 routed experts and six active per token. DeepSeek states that the architecture, tokenizer and chat format are unchanged from V4.1 Flash, so switching is a change of model name.

Key strengths. Image and text input in one model, a 1M-token context window, and open weights under the MIT licence. Tool use, structured output and reasoning effort levels were confirmed on the serving endpoint by Stav's own tests on 19 October 2026. DeepSeek reports better scores than V4.1 Flash on agentic coding and terminal benchmarks; those figures come from the vendor's model card, not from an independent benchmark.

When to use it. Use it where you would use V4.1 Flash and want the newer checkpoint: long documents or conversations that would otherwise need chunking, workloads that mix images and text, and agentic or multi-step tasks where you raise the reasoning effort only when a query needs it.

Limitations. Independent benchmarks are not yet available for this checkpoint, and the training data cutoff, total parameter count and maximum output length have not been published by DeepSeek. Stav's tests confirm that tool use, structured output and reasoning levels work, but not how well. Output length is bounded by the serving provider.