Open source · React library
Formosaic: config-driven React forms
Define a form once as JSON, and a rules engine handles conditional logic, validation, wizards, and auto-save. It renders through 11 UI library adapters.
- Role
- Author and maintainer
- Period
- 2026 to present
- Status
- Published on npm
Overview
Formosaic is a React form library where a form is one configuration object: fields, validation, ordering, and declarative rules. When field A changes to a value, rules can make field B required, hide field C, or change field D's options, without code in your components.
The library is MIT licensed. Around it I built formosaic.com: documentation, a live playground, and a visual form designer, with accounts and billing for the hosted product.
Design decisions
- A UI-agnostic core built on React Hook Form, with adapters for 11 UI libraries including Fluent UI, MUI, Ant Design, Chakra, Mantine, Radix, and React Aria.
- Rules declared as data, with 20 condition operators.
- Multi-step wizards with conditional step visibility and rules that reach across steps.
- Auto-save with debounce, retry, and abort.
- Open core. The library and its adapters stay public, and the designer and hosted product live in a separate private repository that pulls the public docs in as a submodule.
Technologies
- React 19
- TypeScript
- React Hook Form
- Vitest
- Storybook
- Next.js
- Clerk
- Stripe