DeepSeek launches V4.1-Flash and retires V4-Pro

DeepSeek launched DeepSeek-V4.1-Flash on September 10 as a 552-billion-parameter mixture-of-experts model with a Causal Encoder-Decoder architecture, 8 billion active parameters on input and 16 billion on output, and native visual understanding. The API model name is deepseek-flash; V4-Flash and V4-Flash-Vision-Exp are retired, with compatibility aliases routing to V4.1-Flash. Starting at 04:00 UTC on September 14, all deepseek-v4-pro requests route to V4.1-Flash at Flash rates until V4.1-Pro launches, and new peak/off-peak pricing (off-peak at 50 percent of peak) took effect at 04:00 UTC on September 10.