Zod

Zod delivers TypeScript-first schema validation with zero dependencies and automatic type inference.

Zod bridges the gap between runtime input and static TypeScript types. Developers define a schema once (e.g., `z.object({ id: z.uuid() })`) to gain both validation and automatic type inference. This library processes over 12 million weekly npm downloads, securing its position as the standard for type-safe data handling. It eliminates the "any" type by parsing raw data into structured, validated objects. The 8kb footprint (minified and zipped) works across any environment: Node.js, browsers, or Edge functions. It handles complex logic like discriminated unions and transformations without requiring a separate build step.

https://zod.dev