How to integrate Buttons and RSVP Forms with Next.js

This guide uses the Next.js App Router with React 19. React 19 supports Web Components directly. Use the core add-to-calendar-button package and the <add-to-calendar-button> element.

Step 1: npm installation

npm install add-to-calendar-button

Step 2: Create your component

app/components/event-button.tsx:

'use client';

import 'add-to-calendar-button/styles/all';
import 'add-to-calendar-button/i18n/de';
import 'add-to-calendar-button';

export default function EventButton() {
  return (
    <add-to-calendar-button prokey="prokey-of-your-event"></add-to-calendar-button>
  );
}

Your event data, styles, and RSVP settings remain connected to the PRO app through the prokey.

Import this Client Component into your page:

// app/page.tsx
import EventButton from './components/event-button';

export default function Page() {
  return <EventButton />;
}

The 'use client' directive marks the interactive component. A separate SSR entry can also pre-render a button shell; see below.

Step 3: Add the custom element TypeScript declaration

Register the JSX type once in a declaration file included by your tsconfig.json. JavaScript projects can skip this step.

// src/global.d.ts
import type { AddToCalendarButtonType } from 'add-to-calendar-button';
import type { DetailedHTMLProps, HTMLAttributes } from 'react';

declare module 'react' {
  namespace JSX {
    interface IntrinsicElements {
      'add-to-calendar-button': DetailedHTMLProps<
        Omit<HTMLAttributes<HTMLElement>, keyof AddToCalendarButtonType>,
        HTMLElement
      > & AddToCalendarButtonType;
    }
  }
}

export {};

If compilerOptions.types is set, include react and react-dom alongside its existing entries. For example, preserve vite/client in a Vite project.

Bring your own button

Use atcb_action from the core package in a React click handler to open the button or form as a modal. Pass the trigger element for focus handling.

'use client';

import { atcb_action } from 'add-to-calendar-button';

export default function CustomEventButton() {
  return (
    <button
      onClick={(event) =>
        atcb_action({ prokey: 'prokey-of-your-event' }, event.currentTarget)
      }
    >
      Open event
    </button>
  );
}

Styles and languages

The npm package includes only the default style and English by default. The example mixes add-to-calendar-button/styles/all with add-to-calendar-button/i18n/de, which is valid: use add-to-calendar-button/styles/3d when your style is fixed, or add-to-calendar-button/styles/all when remote PRO configuration can change it without deployment. Import the specific language or small known set, such as add-to-calendar-button/i18n/de, by default; use add-to-calendar-button/i18n/all only when languages can change unpredictably at runtime. Both /all imports increase the bundle because they include every respective asset.

Alternatively, load styles and languages dynamically from jsDelivr by setting style-source="https://cdn.jsdelivr.net/npm/add-to-calendar-button@3/dist/styles/" on the element. Apply the same strategy to custom triggers; the option is named styleSource in atcb_action.

Optional: Server-side rendering

The package provides a separate SSR entry to pre-render a button shell. Use its asynchronous variant on the server for PRO data. Full interaction and RSVP forms still initialize in the browser. See SSR with PRO and the Button Next.js guide.