validate

A declarative, cross-environment validation library for JavaScript that treats constraints as pure data.

Validate.js provides a streamlined way to handle data integrity across both browser and Node.js environments. It relies on a declarative syntax: you define a JSON object of constraints (like presence, email format, or numericality) and run your data against it. The library returns a structured list of errors or undefined if the input passes. By keeping validation logic decoupled from UI components or database schemas, it ensures consistent business rules across the entire stack. It is lightweight (under 2kb gzipped) and carries zero dependencies, making it a reliable choice for high-performance production builds.

https://validatejs.org