Formswith

formswith is a lightweight, modular library for building, rendering, and validating web forms. It emphasizes a declarative approach in which a form is defined by a schema rather than by imperative UI code. The library is framework-agnostic, designed to slot into vanilla JavaScript projects or be dropped into popular front-end frameworks through adapters.

Core concepts include a form schema, field definitions, validation rules, and a rendering layer composed of pluggable widgets. The validation engine supports synchronous and asynchronous validators, custom error messages, and localization-friendly error keys. Forms are built from reusable field components such as text input, checkbox, radio group, select, and file input, with support for built-in accessibility features, keyboard navigation, and screen-reader labels.

Architecture and extensibility: a core API handles form state and events, while a plugin system allows developers to add new field types or integrate with state management libraries. Data binding supports two-way binding between the form state and the UI, with optional server-side validation hooks.

Usage: a form is declared as a JSON/YAML-like schema or a fluent API; the rendering layer maps schema to UI widgets; on submission, validation is run and errors are surfaced inline. Formswith can serialize form data for submission to a back end and can handle partial updates.

History and status: the project emerged in the open-source ecosystem as a response to the complexity of bespoke form handling. It remains community-maintained with an MIT-style license; adoption varies by project, with several bindings and adapters available.

See also: Formik, React Hook Form, validation libraries.