Arena.ai (@arena) · 10/24/2026, 01:41:48
Kimi K3.1 Pro Launches with Code Arena Jump Rivaling Claude Opus-5
Moonshot AI released Kimi K3.1 Pro, which jumped to #8 in the Code Arena: WebDev leaderboard, matching Claude Opus-5 (Max) scores at 70% lower cost. The model features a 2.8T total/104B active parameter MoE architecture with 1M-token context and will soon open-source weights, potentially overtaking DeepSeek-v4.1-Flash as the top open coding model.
SOURCE COVERAGEFull Original Report
Arena.ai (@arena) · 2026-10-23 17
Big news: @Kimi_Moonshot is back in the top-4 labs in the Code Arena: WebDev with the release of Kimi K3.1 Pro!
This model just landed #8 in the Code Arena: WebDev with 1692 pts, matching Claude Opus-5 (Max) at 70% lower cost. This is a 9 place jump (+37 points) from Kimi K3 (Max) at #17 with 1655 pts.
Kimi K3.1 Pro improved from Kimi K3 across all categories. Highlights:
- #7 in Brand & Marketing (up from #9)
- #9 in Simulations (up from #20)
Cost efficiency is another upgrade. Priced at 10 per million input/output tokens, Kimi K3.1 Pro (Max) has a median cost per task of $1.23 (29% less than Kimi K3). See its placement compared to the Pareto frontier in thread.
With open weights coming soon, Kimi K3.1 Pro would be the new #1 open model in the Code Arena: WebDev, overtaking DeepSeek-v4.1-Flash. Stay tuned!
See @Kimi_Moonshot’s ranking by lab, and 3D generations from Kimi K3.1 Pro below in thread.
Huge congrats to the @Kimi_Moonshot team on this release!
↳ 引用 @Kimi_Moonshot (Kimi.ai): Introducing Kimi K3.1 Pro: our most capable 3T-class open-weight model.
🔹 1M-token context, 2.8T total / 104B active params (MoE), Multimodal. 🔹 Full-project coding: games in Unreal, Unity & Godot. 🔹 Excels at parametric 3D modeling in Blender & CAD. 🔹 More reliable at finance work: Accurate modeling with hallucination down by 65%. 🔹 Matching the strongest proprietary models across coding, agentic and knowledge benchmarks.
Kimi K3.1 Pro and K3.1 Pro Highspeed (2–3× faster) are now live on
