StandardDeviationTools is a lightweight calculator suite for working with variability and averages in real-world datasets. It includes dedicated views for single-sample standard deviation, pooled standard deviation across groups, and sum-based calculations, with clear step-by-step inputs and live results. You can add, edit, and review records, track calculation history, and quickly reuse previous datasets. Helpful onboarding and in-app help explain formulas, assumptions, and interpretation, while settings let you customize defaults and appearance. Designed for students, researchers, and data-curious professionals, the app emphasizes clarity, transparency, and reproducibility—showing intermediate values and notes—so you can focus on decisions, not manual math or spreadsheets.