DeepSeek-V4.1-Flash takes the top open model spot in Code Arena

DeepSeek has a new title to its name. Its DeepSeek-V4.1-Flash-20261017 model is now the highest-ranked open model on Arena.ai’s Code Arena WebDev leaderboard. It got there by beating Kimi K3 (Max) while costing roughly a tenth as much to run. What the leaderboard shows Arena.ai posted the update on October 18, 2026. It showed the new DeepSeek build scoring 1670 points on Code Arena WebDev. That score puts it at #1 among open models and #12 overall. The leaderboard covers agentic and front-end coding tasks. The model it displaced at the top of the open rankings is Kimi K3 (Max). Arena.ai pegged the cost advantage at approximately 10x lower than Kimi K3 (Max). The platform also framed the release as shifting the performance-cost Pareto frontier for open models in coding workflows. A point release that punches above its version number The October 17 build is technically a minor update. It refreshes the DeepSeek model that launched in September 2026. Minor, in this case, still means better on every benchmark DeepSeek listed. A few comparisons against the September version stand out: DeepSWE v1.1: 77.0, up from 74.2. Terminal-Bench 4.0: 42.3, up from 31.2. Automation-Bench: 60.5, up fro...