Overview
- DeepSeek began a short internal test on Tuesday, September 8, 2026 for a middle-version model called DeepSeek V4.1 Flash that the company announced in its official community.
- Developers can call the test endpoint by setting the model name to deepseek-v4.1-flash-expires-on-0910 using the existing API base_url, and the endpoint appears set to expire on September 10.
- DeepSeek says V4.1 Flash uses a new model structure with native multimodal support and claims the build delivers stronger capability, faster generation and lower cost compared with prior Flash releases.
- The test runs at existing V4 Flash pricing with a 20-concurrency cap per account, public documentation and a changelog have not been updated, and DeepSeek is collecting tester feedback through a questionnaire.
- Early third-party hands-on checks report clear speed gains and better short-form writing and UI/interaction outputs but mixed results on large integrated tasks, and the company has asked testers whether Flash could fully replace V4 Pro.