DeepSeek open-sources V4.1-Flash with a radically smaller long-context memory footprint
DeepSeek released the MIT-licensed weights and technical report for V4.1-Flash, a native multimodal mixture-of-experts model supporting contexts up to one million tokens. Its new causal encoder-decoder and sparse-attention design activates 8B parameters during prompt ingestion and 16B during generation while reducing global KV-cache memory to 890 bytes per token—about one-quarter of V4-Flash—and persistent cache storage to one-eighth.
Why it made the cut: This is a consequential open model and a serving-architecture advance aimed directly at long-running coding and research agents, where repeatedly processing large contexts is a central cost. DeepSeek reports that V4.1-Flash also surpasses its much larger V4-Pro on several agentic evaluations, including DeepSWE and Terminal-Bench; those capability results remain vendor-reported, but the released weights, implementation guidance, and benchmark-reproduction instructions make the efficiency claims unusually inspectable.
Technical report · Official announcement · Model weights and evaluation code · Independent technical analysis
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