Moonshot AI dropped Kimi K3 on July 16. Within hours of release it landed at #1 on LMArena's Frontend Code Arena, displacing Claude Fable 5. The model is 2.8 trillion parameters, sparse MoE with a 1M-token context window, priced at $3 per million input tokens and $15 per million output. Fable 5 costs $10/$50. On the surface that's a 3x cost reduction from a model that just beat it on a prominent coding benchmark. The full weights drop July 27 under a Modified MIT license. This is a good story. It's also a bit more complicated than the headline suggests. What's actually new in the architecture The 2.8T parameter count is real but misleading as a measure of compute. Kimi K3 is a sparse MoE model with 896 experts and activates only 16 per token, roughly 1.8% of the total pool. The active compute per inference is a fraction of what that headline number implies. The genuinely novel pieces are Kimi Delta Attention (KDA) and Attention Residuals (AttnRes). KDA is a hybrid ...