Kimi K3.1 Pro First Impressions: Has Moonshot Caught Up to the Frontier?

https://arena.ai/agent Peter Gostev puts Moonshot’s Kimi K3.1 Pro, the follow-up to the open-weight Kimi K3, through 3D scenes, HTML animations, website and UI builds, and research-driven pages. He compares it with Kimi K3, Opus 5.5, Sonnet 5.5, GPT 6.1 Sol, GPT 5.6 Sol, Gemini 4 Argon, DeepSeek 4.1 Flash, and the Muse Wonder models. Peter’s take: Kimi K3.1 Pro is a huge jump over K3, but in these tests it’s not quite at the frontier, and cost is a big part of the story. Note on pricing: K3.1 pricing wasn’t available when this was recorded, so the costs shown use Kimi K3 prices. The actual cost is approximately a third lower. Peter’s prompts: https://github.com/petergpt/3d-prompt-collection 0:00 3D scene: dinosaurs 3:12 3D scene: bears and salmon 7:32 3D scene: Acropolis 9:38 3D scene: Roman town center (voxel) 12:21 3D scene: Tower of Babel 14:55 HTML story: first example 16:43 HTML story: Taj Mahal 17:45 HTML animation: Trojan horse on a vase 19:24 HTML scene: Venice 20:34 Animation: train delivering mail 22:46 Website: ramen shop 27:07 Website: toy store 29:26 Data layout: Grand Prix 32:22 Research UI: alpine walk 35:06 Research UI: data center map 38:19 Research UI: shopping comparison 39:19 Closing thoughts on competition and cost 41:19 Claymation example #arenaai #moonshotai #opensource #llm