Just two days after its launch, DeepSeek-V4.1- Flash-1017 has become the top open model in Code Arena WebDev leaderboard, surpassing Kimi K3 model, owing to the “Pareto improvement” in model’s agentic front-end tasks performance and lower cost.
According to Arena AI, DeepSeek Flash v4, which was updated by Chinese startup DeepSeek AI on October 17, has quickly risen in ranks among top open models scoring 1670 points and ranking 12th overall.
Exciting news: DeepSeek-V4.1-Flash-20261017 (Max) by @deepseek_ai is now the #1 open model in Code Arena: WebDev, surpassing Kimi K3 (Max) at 10x lower cost!
Highlights:
– #1 open model, ahead of Kimi K3 (Max)
– #12 overall with 1670 pts, ahead of Claude Opus 5 (High) and within ~10 pts of GPT-6 Sol (Max)
– Shifts the Pareto frontier at $0.3/$1.2 per million input/output tokens
– +52 pts vs. the previous DeepSeek-V4.1-Flash-20260910Congrats to the @deepseek_ai team on another strong contribution to the open source ecosystem!
— Arena.ai (@arena) October 18, 2026
The AI model edges past Kimi K3 (Max) while running at roughly one-tenth the cost, priced at $0.30 per million input tokens and $1.20 per million output tokens.
On October 17, DeepSeek launched DeepSeek-V4.1- Flash-1017, an updated version of its AI model that the company says delivers stronger benchmark performance, faster task completion and shorter outputs than its predecessor.
Built as a Mixture-of-Experts architecture , the new model is available on DeepSeek’s website, mobile app and application programming interface. The company has described the update as a “Pareto improvement” in performance and cost, indicating that it aims to improve performance while maintaining or reducing the cost of using the model.
🚀 DeepSeek-V4.1-Flash-1017 is here!
Stronger benchmark performance, faster task completion, and shorter outputs than the previous version—a Pareto improvement in performance and cost. Now live on our website, app, and API.
🛠️ Optimized for @DeepSeekHarness, Tencent CodeBuddy, WorkBuddy, and more. Upgrade to DeepSeek Harness v0.2.1-rc.1 or later for the best experience with the new model.
1/4
— DeepSeek (@deepseek_ai) October 17, 2026
DeepSeek-V4.1- Flash-1017 is designed to support end-to-end project development, including building complete projects from scratch. According to the company the model uses reinforcement learning with self-feedback to improve its ability to execute complex tasks, ranging from game development to 3D modelling.
Architecturally, it builds on the V4.1-Flash multimodal Mixture-of-Experts design (approximately 552B backbone parameters plus Engram components). It uses a Causal Encoder-Decoder structure that activates only about 8B parameters during prefill and 16B during decode, supporting a 1-million-token context window and native image-text inputs.
The model has also been optimized for AI development tools, including DeepSeek Harness and Tencent’s CodeBuddy and WorkBuddy. DeepSeek has recommended upgrading to DeepSeek Harness version 0.2.1-rc.1 or later to get the best experience with the new model.
Alongside the model launch, DeepSeek has opened its Search and Fetch APIs to all users. The APIs are powered by the company’s in-house search engine, which says it handles hundreds of millions of requests worldwide everyday.
The company has priced each API endpoint at $0.75 per 1,000 calls. The newly available services are intended to enable developers to integrate search and information retrieval capabilities into their applications.
The launch expands DeepSeek’s offerings for developers seeking AI tools for coding, project creation and information retrieval.
Also Read: DeepSeek V4 Model Unveiled: China’s Cost Effective GenAI Push






