Moonshot AI releases Kimi K3, a 2.8T-parameter open-weights multimodal model
Moonshot AI released Kimi K3 on 2026-07-16: a 2.8T-parameter MoE (~104B active) with a 1M-token context and native image/video input — the largest open-weights model to date — which Fortune reported as competitive with Anthropic's Claude Fable 5 while costing $15/M output tokens vs Fable 5's $50.
Key facts
- 2.8T total parameters, ~104B activated (16 of 896 experts per token + 2 shared) per Hugging Face model card
- Context window: 1,048,576 tokens; 401M-parameter MoonViT-V2 vision encoder; weights released in MXFP4 with MXFP8 activations
- Architecture: Kimi Delta Attention + Gated MLA layers, Stable LatentMoE, Attention Residuals
- Model card benchmarks: GPQA Diamond 93.5, BrowseComp 91.2, Terminal-Bench 2.1 88.3, DeepSWE 67.5, Video-MME 90.0
- API pricing: $3/M input, $15/M output (vs $50/M output for Claude Fable 5 cited by Fortune)
- ARC Prize: 94.5% ARC-AGI-1, 60.4% ARC-AGI-2
- License: custom Kimi K3 License (separate agreement for MaaS businesses >$20M revenue; attribution above 100M MAU)
- Listed on Amazon Bedrock 2026-09-18 (secondary report)
What happened
Moonshot AI launched Kimi K3 on 2026-07-16 as a native multimodal, agentic flagship. The Hugging Face model card lists 2.8T parameters with ~104B active, a 1M-token context, and MXFP4 weights produced with quantization-aware training. Fortune (which gave 2.7T) reported Moonshot's claims of being competitive with Anthropic's Claude Fable 5 and substantially outperforming Claude Opus 4.8 and GPT-5.5, particularly at long-running coding sessions and terminal tool orchestration. Weights followed on Hugging Face by late July. Moonshot also claimed an official 42/42 on IMO 2026 problems (per commentary quoted by TechXplore; not independently confirmed here).
Why it matters
K3 made the "open-weights frontier" roughly one step behind the very best closed models, at a fraction of their price, and the weights are downloadable by anyone — a major data point in the US-China model race and for open-model policy debates.
Changelog
- 2026-09-29: created
Related events
- AI systems score a perfect 42/42 at IMO 2026, officially graded ★★★★★
- Alibaba launches Qwen3.8-Max (2.4T MoE) and open-sources the Qwen3.8 family ★★★★
- Thinking Machines Lab releases Inkling, its first open-weights model (975B MoE) ★★★★
Sources (4)
- officialHugging Face: moonshotai/Kimi-K3 model card
- pressFortune: Kimi K3 pushes Chinese AI into Fable-level territory
- pressBloomberg: Moonshot unveils Kimi K3, narrowing gap with US rivals
- discussionARC Prize results
id: 2026-07-16-moonshot-kimi-k3 · updated 2026-09-29 · open in the interactive timeline