Shape is a lightweight, dependency‑free JavaScript/TypeScript library for defining and validating data schemas. It lets developers describe expected objects, arrays, and primitive values by writing example data (with optional defaults) and provides a rich set of “shape builders” for required fields, custom checks, length constraints, open/closed objects, recursion, etc., mutating the input to inject defaults and throwing detailed errors when validation fails. The tool is aimed at Node and browser developers who need an easy‑to‑read, “schema‑by‑example” validator for configuration options, API payloads, or component props.