Validate Formhaus form definitions and simulate multi-step paths against the real engine.
Add Formhaus to your coding agent
npx formhaus
Adds the Formhaus MCP server to Claude Code, Codex, Cursor and Claude Desktop. Writes, checks and repairs definitions locally, with no account · Setup for each client
Two independent ways to use it:
Use the library. MIT, no account, no key. The core is framework-agnostic and runs the form in any app; React and Vue renderers are ready to use. Your submit handler sends the data wherever you want. CI tests React 18 and 19, and Vue 3.3 and 3.5.
npm install @formhaus/core # plus @formhaus/react or @formhaus/vue
Use Formhaus Cloud. A hosted form backend: a submission endpoint with server validation, a dashboard and webhooks, plus hosted links, embeds and a visual builder. The first form needs no account.
Build in the browser at app.formhaus.dev, or add the remote MCP server and ask your agent: "Make me a waitlist form and give me the link."
claude mcp add --transport http formhaus https://api.formhaus.dev/mcp

| Feature | |
|---|---|
| One definition | Fields, validation, conditional fields, steps, branching routes, sections and repeatable groups in one JSON file you keep in git |
| React and Vue | Native renderers with accessible defaults, or your own components through components |
| Validation | Built-in rules and custom validators. validateSubmission() checks the same definition on the server |
| Agents | The MCP server writes, validates and fixes definitions. Remote MCP publishes forms and reads responses |
| i18n | Translation catalogs and keys for labels, messages and options |
| Accessibility | Labels, error summary, focus management and live regions built in |
| Small core | Zero dependencies, tree-shakable ESM |
| Figma | The plugin renders mockups, flow maps and prototypes from the same definition |
| Cloud, optional | Hosted links, embeds, a submission endpoint, CSV export and webhooks |
claude plugin marketplace add formhaus-dev/formhaus && claude plugin install formhaus@formhaus), the JSON Schema and the format specification.Business accounts get a company step; everyone converges on review.
{
"$schema": "https://formhaus.dev/schema/form-definition.json",
"id": "signup",
"title": "Sign up",
"submit": { "label": "Create account" },
"steps": [
{
"id": "account",
"title": "Account",
"fields": [
{ "key": "email", "type": "email", "label": "Email", "validation": { "required": true } },
{ "key": "kind", "type": "radio", "label": "Account type", "autoAdvance": true,
"options": [{ "value": "personal", "label": "Personal" }, { "value": "business", "label": "Business" }] }
],
"routes": [
{ "to": "company", "show": [{ "field": "kind", "eq": "business" }] },
{ "to": "review" }
]
},
{ "id": "company", "title": "Company", "routes": [{ "to": "review" }],
"fields": [{ "key": "company", "type": "text", "label": "Company name", "validation": { "required": true } }] },
{ "id": "review", "title": "Review",
"fields": [{ "key": "terms", "type": "checkbox", "label": "I accept the terms", "validation": { "required": true } }] }
]
}
import { FormRenderer } from '@formhaus/react';
import definition from './signup.json';
<FormRenderer definition={definition} onSubmit={save} />;
Compare with react-hook-form, TanStack Form, react-jsonschema-form and SurveyJS →
| Package | Description | npm |
|---|---|---|
@formhaus/core | Zero-dependency form engine: types, validation, visibility, multi-step | npm i @formhaus/core |
@formhaus/react | React adapter with native HTML defaults and custom component support | npm i @formhaus/core @formhaus/react |
@formhaus/vue | Vue 3 adapter with native HTML defaults and custom component support | npm i @formhaus/core @formhaus/vue |
@formhaus/mcp | MCP server: validate definitions and simulate paths from AI agents | claude mcp add formhaus -- npx -y @formhaus/mcp |
@formhaus/figma generates form mockups on the Figma canvas. It is not on Figma Community yet; build it locally, then import packages/figma/manifest.json.
Svelte, Solid, or anything else: use @formhaus/core directly. The playground has a Svelte example.
npm install @formhaus/core
If you need a framework adapter:
npm install @formhaus/core @formhaus/react # React
npm install @formhaus/core @formhaus/vue # Vue
Or use @formhaus/core directly with any framework. See the Svelte example.
Write the JSON by hand, or use the /formhaus:formhaus-create-form Claude Code skill to generate it from a text description, a CSV table, or a screenshot of an existing form.
{
"$schema": "https://formhaus.dev/schema/form-definition.json",
"id": "contact",
"title": "Contact Us",
"submit": { "label": "Send" },
"fields": [
{
"key": "name",
"type": "text",
"label": "Name",
"placeholder": "Your name",
"validation": { "required": true, "minLength": 2 }
},
{
"key": "email",
"type": "email",
"label": "Email",
"placeholder": "you@example.com",
"validation": {
"required": true,
"pattern": "^[^\\s@]+@[^\\s@]+\\.[^\\s@]+$",
"patternMessage": "Please enter a valid email address"
}
},
{
"key": "message",
"type": "textarea",
"label": "Message",
"placeholder": "How can we help?",
"rows": 4,
"validation": { "required": true }
}
]
}
npm install @formhaus/core @formhaus/react
import { FormRenderer } from '@formhaus/react';
import definition from './contact-form.json';
function ContactPage() {
async function handleSubmit(values: Record<string, unknown>) {
await fetch('/api/contact', {
method: 'POST',
body: JSON.stringify(values),
});
}
return <FormRenderer definition={definition} onSubmit={handleSubmit} />;
}
npm install @formhaus/core @formhaus/vue
<script setup lang="ts">
import { FormRenderer } from '@formhaus/vue';
import definition from './contact-form.json';
async function handleSubmit(values: Record<string, unknown>) {
await fetch('/api/contact', {
method: 'POST',
body: JSON.stringify(values),
});
}
</script>
<template>
<FormRenderer :definition="definition" @submit="handleSubmit" />
</template>
By default, both adapters render native HTML inputs. A step can hide Next with next: false, and cancellable async hooks run before and after navigation and submission. See lifecycle hooks.
Both adapters accept a components prop (a FieldComponentMap) that lets you swap native HTML inputs for your own UI kit.
import type { FieldComponentMap, FieldComponentProps } from '@formhaus/react';
function MyTextInput({ field, value, error, onChange, onBlur }: FieldComponentProps) {
return (
<div>
<label>{field.label}</label>
<input
type={field.type}
value={(value as string) ?? ''}
placeholder={field.placeholder}
onChange={(e) => onChange(e.target.value)}
onBlur={onBlur}
/>
{error && <span className="error">{error}</span>}
</div>
);
}
const components: FieldComponentMap = {
text: MyTextInput,
email: MyTextInput,
};
<FormRenderer definition={definition} onSubmit={handleSubmit} components={components} />;
<script setup lang="ts">
import type { FormFieldProps } from '@formhaus/vue';
const props = defineProps<FormFieldProps>();
const emit = defineEmits<{ (e: 'update:modelValue', value: unknown): void }>();
</script>
<template>
<label>{{ props.field.label }}</label>
<input
:value="(props.modelValue as string) ?? ''"
@input="emit('update:modelValue', ($event.target as HTMLInputElement).value)"
/>
</template>
<script setup>
import { FormRenderer } from '@formhaus/vue';
import MyTextInput from './MyTextInput.vue';
</script>
<template>
<FormRenderer
:definition="definition"
:components="{ text: MyTextInput, email: MyTextInput }"
@submit="handleSubmit"
/>
</template>
Each field component receives the full FormField descriptor, the current value, and any validation error. Implement as many or as few field types as you need. Unmapped types fall back to native HTML.
@formhaus/figma renders form definitions in Figma with built-in Material 3 and iOS-like kits or with your own components. Branching forms get a flow map, multi-step forms a clickable prototype, and a generated form can be selected, edited and updated in place.

The /formhaus:formhaus-figma-connect Claude Code skill binds your library's components to the plugin. See the plugin guide for local installation.
See CONTRIBUTING.md.
Source-derived launch command. Check the maintainer’s required arguments and credentials before running:
npx -y @formhaus/mcpMerge this template into ~/Library/Application Support/Claude/claude_desktop_config.json. Keep existing servers. Add any arguments, credentials, and permissions required by the maintainer; this template has not been install-tested.
{
"mcpServers": {
"io-github-formhaus-dev-formhaus": {
"command": "npx",
"args": [
"-y",
"@formhaus/mcp"
]
}
}
}Restart Claude Desktop completely for changes to take effect. Confirm the server appears connected in the client’s tool list, then try a read-only example from its documentation.
Claude Desktop setup reference@formhaus/mcpnpmFormhaus works with any MCP-compatible client. Copy the config snippet from the Configuration section above and add it to the file shown for your client, then restart the application.
~/Library/Application Support/Claude/claude_desktop_config.jsonRestart Claude Desktop completely for changes to take effect.~/.cursor/mcp.jsonRestart Cursor for changes to take effect..vscode/mcp.jsonReload VS Code window for changes to take effect.~/.codeium/windsurf/mcp_config.jsonRestart Windsurf for changes to take effect..mcp.jsonSave at the project root, then start Claude Code in that project and review the MCP server approval prompt. Keep real credentials out of shared files.