A fast and modular iCalendar generator entirely written in TypeScript

Usage no npm install needed!

<script type="module">
  import icalGen from 'https://cdn.skypack.dev/ical-gen';



Build Status NPM version Size MIT License

ical-gen is a super-small library that lets you easily create valid iCalendar files or feeds in Node.js.

ical-gen is a fork of the amazing ical-generator library by Sebastian Pekarek, which has more features and is probably generally better supported by its author than this brand new library.

Warning: This library is an early draft with only a small subset of features of the original and certainly not production ready. The API is likely to change significantly until the first stable release has been reached.

Warning: This version of README relates to the latest push to the main branch on GitHub, not necessarily to the latest NPM package.

📦 Installation

yarn add ical-gen
# or
npm install ical-gen

⚡️ Quick Start

import { ICalCalendar, ICalEvent } from 'ical-gen';

// Instantiate a new calendar component:
const calendar = new ICalCalendar({
    prodId: {
        company: 'My Company X',
        product: 'My Product Name',
        language: 'EN',
    // ...add more calendar options if you like...

// Instantiate a new event component:
const event = new ICalEvent({
    uid: 'MyUniqueUID@example.com', // or supply a UUID
    // An event date can be represented either by a native JS Date and a time zone
    // string or, if you like, a Luxon DateTime object. Let's use a Date for the
    // start date:
    start: {
        date: new Date('2021-05-17T18:30:00Z')
        zone: 'Europe/London',
    // And let's use a Luxon Datetime for the end date:
    end: DateTime.fromISO('2021-05-16T00:00:00Z', { zone: 'Europe/London' }),
    // For the stamp we can safely use a Date, because no time zone information is required.
    stamp: new Date('2021-05-16T00:00:00Z'),
    sequence: 1,
    summary: 'My Birthday Party',

// Add the event component as child of the calendar component:
// or directly:

// Render the iCalendar file or feed. This is asynchronous, because it enables
// us to do dynamic data fetching if needed, for example to resolve time zone
// components from a time zone database.
const ics = calendar.renderToString()
    .then(ics => {
        // Then do whatever you want with that string. Serve it over HTTP,
        // write it to a file, send it by email or print it to the console:

Why another library?

Although the original ical-generator is great, it comes with support for several different third-party date libararies, HTTP server output, validation and more, which are not always needed. This convenience adds some bulk and may slow things down. Personally, I ran into some TypeScript issues using ical-generator without also installing third-party libraries in my project.

The goals for this library are:

  • efficient and fast processing speed
  • clean, simple and strict TypeScript API
  • predictable results
  • (near) zero dependencies for the production build

Some differences

Some differences between ical-generator and ical-gen (this library):

  • This library only supports JavaScript-native Date objects as date. If you work with Moment.js, Day.js or Luxon, simply convert the date object to a native Date and apply the time zone string where applicable.
  • Experimental: This library uses Luxon DateTime objects internally and accepts either DateTime objects (with its time zone) or native JavaScript Date as event date input.
  • The API will be completely rewritten. It will be modular, extensible, componsable, less opinionated, hopefully also cleaner, and with more predictable results. Examples:
    • If a property is required, it will be enforced by the TypeScript API right away instead of throwing a runtime error later down the line.
    • Class properties can usually be accessed and manipulated directly, which saves us a whole lot of getter, setter and other helper methods. As long as you know how to assign a new value to a variable or push() an item to an array, you can do everything you want.
  • Every iCalendar component will be represented by its own component class, e.g. a root ICalCalendar component, that can have one or more ICalEvent child components as well as ICalTimeZone components.
  • The way data is stored internally is different with an aim to be more efficient.
  • ical-generator always generates a UUID string for the UID property when a new event is created, which you can then override with a custom value. With ical-gen you must always provide your own UID value. If you really, really need a universally unique value that is always different whenever you render the event (which you shouldn’t), apply your own UUID method.
  • At least for now, this library is meant to be used in Node.js 11.15 or later, not in a browser environment.
  • The render function returns a Promise. This allows any component to do async stuff on the fly if needed without blocking. For example, to resolve time zone data more efficiently.


  • A lot more iCalendar components need to be implemented:
    • ICalEvent (it’s still a big mess and only a basic draft)
    • ICalAlarm
    • ICalAttendee
    • ICalCategory
    • and probably more
  • More tests as more components are implemented
  • Evaluate whether to keep Luxon or reduce to plain Date
  • Provide a basic implementation for resolving time zone strings to iCalendar time zone components.