The synthetic control methodology (Abadie and Gardeazabal, 2003, American Economic Review 93: 113–132; Abadie, Diamond, and Hainmueller, 2010, Journal of the American Statistical Association 105: 493–505) allows for a data-driven approach to small-sample comparative studies. synth runner automates the process of running multiple synthetic control estimations using synth. It conducts placebo estimates in space (estimations for the same treatment period but on all the control units). Inference (p-values) is provided by comparing the estimated main effect with the distribution of placebo effects. It also allows several units to receive treatment, possibly at different time periods. It allows automatic generation of the outcome predictors and diagnostics by splitting the pretreatment into training and validation portions. Additionally, it provides diagnostics to assess fit and generates visualizations of results.