# Overview

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`form0-core` is the schema-driven engine that powers calculations, visibility, requirements,
validation, and events. It is framework-agnostic and runs in any JavaScript runtime (Node.js,
browsers, React Native, etc.).

## ⚙️ What form0-core does

- Validates form schemas and field definitions
- Evaluates calculated fields and expressions
- Applies visibility, required, and read-only conditions
- Runs events defined in `form.events.code`
- Exposes structured state (`values`, `errors`, `visible`, `required`, `read_only`)
- Produces structured records for submission

## 🚫 What form0-core does not do

- UI rendering or layout
- Data persistence or networking
- Authentication or user management

<Callout type="info" title="Application-level attributes and field types">
  Some schema attributes are application-level metadata, and certain field types require interaction
  with other forms in your application, so they are not processed directly by the engine. These
  attributes and field types are still accepted by the engine. They can be used when integrating
  with [reform](https://reformapp.io), the SaaS product built by [paqu
  technologies](https://paqu.io) (the team behind form0), or when building similar functionality in
  your own application.
  <br />
  For more details, see [form attributes](/core/schema/form) and [field
  types](/core/fields/catalog).
</Callout>