*lazar* (lazy structure–activity relationships\cite{Maunz2013}) is a modular framework for predictive toxicology. Similar to the read across procedure in toxicological risk assessment, *lazar* creates local QSAR (quantitative structure–activity relationship) models for each compound to be predicted. Model developers can choose between a large variety of algorithms for descriptor calculation and selection, chemical similarity indices, and model building. We provide a high level description of the lazar framework and present the recent end user web interface *lazar* -GUI.