Kimi K3 vs Opus 4.8: What the Open-Weights Challenger Actually Delivers

Moonshot's Kimi K3 is the first open 3-trillion-parameter model, and its makers say it closes the gap with Anthropic's Opus 4.8. Here is what the sources actually show — and how to read the claim.

07/18/2026 · Model Evaluation · 9 min read