formhaus MCP server

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
  

  Cloud quickstart · Connect Claude · Dashboard · Pricing

What you get

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

What it's for

• Multi-step forms with branching in React or Vue.
• Rendering a form from JSON with your own components.
• Designing the form in Figma from the same file.
• Generating and checking definitions with AI agents: Claude Code skills, the MCP server (claude plugin marketplace add formhaus-dev/formhaus && claude plugin install formhaus@formhaus), the JSON Schema and the format specification.
• Translated forms with your own catalogs, or with i18next, vue-i18n and Lokalise keys.
• A headless engine for Svelte or vanilla JS.

Example

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, react-jsonschema-form, JSON Forms and SurveyJS →

Packages

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. See the Svelte recipe.

Install

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 recipe.

Quick start

Define a form

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 }
    }
  ]
}

React

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} />;
}

Vue

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.

Custom components

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} />;

<!-- MyTextInput.vue -->
<script setup lang="ts">
import type { FieldComponentProps } from '@formhaus/vue';

const props = defineProps<FieldComponentProps>();
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>

<!-- Usage -->
<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.

Figma plugin

@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.

Contributing

See CONTRIBUTING.md.

License

MIT