This model can generate upwards of 1,000 tokens per second. Ultrafast serves the October 17 update of DeepSeek V4.1 Flash through Fireworks' accelerated serverless endpoint.
It is suited to interactive coding, reasoning, and agentic workflows where applications need to generate output and move to the next step quickly. The model has a 1M-token context window for working with large codebases and long inputs.
It is available in public preview without a waitroom or session time limit. Use it by setting deepseek/deepseek-v4.1-flash-1017-ultrafast as the model name: To use it in Claude Code, Codex, Cursor, and more, install the latest Vercel CLI and run setup: Then select deepseek/deepseek-v4.1-flash-1017-ultrafast in the agent.
See the coding agents guide for details. Try DeepSeek V4.1 Flash 1017 Ultrafast in the model playground.
