Kimi K3.1 Pro Tops Open Agent Arena with 13% Cost Drop
Moonshot AI released Kimi K3.1 Pro (Max), ranking #11 in the Agent Arena and becoming the top open-weight model. It shows significant improvements over its predecessor, reduces median task cost by 13%, and excels in coding and web development, with weights coming soon.
Full Report
Arena.ai (@arena) · 2026-10-24 14
Kimi K3.1 Pro (Max) by @Kimi_Moonshot just landed in the Agent Arena at #11 with +7.6% net improvement across +4K real-world agentic sessions from our global community of users.
Kimi K3.1 Pro (Max) would be the new #1 open model in the Agent Arena overtaking DeepSeek-v4.1-Flash! Open weights coming soon, stay tuned.
Kimi K3.1 Pro (Max) is a +6 percentage pt improvement over Kimi K3 (Max) at +1.6% (#25 -> #11). And with a $1.03 median cost per task in Agent Arena, Kimi K3.1 Pro is 13% less than its previous variant. See its placement just off the Pareto frontier in thread.
Across Agent Arena categories, Kimi K3.1 Pro (Max) ranks #8 in Work, #9 in Code, and #10 in Chat.
By signal, it’s the strongest in Praise vs. Complaint (implicit sentiment in user reactions) with +19% at #8. Across other signals it landed:
- #11 in Steerability (+8.3%)
- #15 in Bash Reliability (+8.3%)
- #26 in Confirmed Success (+2%)
Huge congrats to the @Kimi_Moonshot team on this release!
↳ 引用 @arena (Arena.ai): 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!
