ScaleCheck is a free, interactive Shiny app for checking the quality of psychological and behavioral scales. It gathers several psychometric methods into one place: descriptive statistics and reliability (Cronbach’s α, McDonald’s ω, GLB), dimensionality assessment (Parallel Analysis, Exploratory Graph Analysis, Hull method), Confirmatory Factor Analysis, Rasch-family IRT models, and tests of monotonicity and local independence. Users can load an example dataset or upload their own, run each analysis on demand, and get an interpretation of the results. Each output comes with the R code that reproduces it. A downloadable HTML report summarizes all findings and flags the items that need review.