OpenRouter sees open-weight models reach 72% tokens

The authors examine the differences between open-weight and closed-weight AI models, finding that open-weight model usage on OpenRouter grew from 27% in late 2025 to 72% in late September 2026. While closed-weight models still score higher on the Artificial Analysis Intelligence Index, open-weight models are significantly cheaper due to provider competition. The authors recommend starting with an open-weight model and routing to a closed-weight model only when necessary. Open article →