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ical.js - Javascript parser for iCalendar, jCal, vCard, jCard.

This is a library to parse the formats defined in the following rfcs and their extensions:

The initial goal was to use it as a replacement for libical in the Mozilla Calendar Project, but the library has been written with the web in mind. This library enables you to do all sorts of cool experiments with calendar data and the web. Most algorithms here were taken from libical. If you are bugfixing this library, please check if the fix can be upstreamed to libical.

Build Status Coverage Status npm version CDNJS

Sandbox and Validator

If you want to try out ICAL.js right now, there is a jsfiddle set up and ready to use.

The ICAL validator demonstrates how to use the library in a webpage, and helps verify iCalendar and jCal. Try the validator online

The recurrence tester calculates occurrences based on a RRULE. It can be used to aid in creating test cases for the recurrence iterator. Try the recurrence tester online.


ICAL.js has no dependencies and is written in modern JavaScript. You can install ICAL.js via npm, if you would like to use it in Node.js:

npm install ical.js

Then simply import it for use:

import ICAL from "ical.js";

If you are working with a browser, be aware this is an ES6 module:

<script type="module">
  import ICAL from "";
  document.querySelector("button").addEventListener("click", () => {

If you need to make use of a script tag, you can use the transpiled ES5 version:

<script src=""></script>
<textarea id="txt"></textarea>
<button onclick="ICAL.parse(document.getElementById('txt').value)"></button>

The browser examples above use the minified versions of the library, which is probably what you want. However, there are also unminified versions of ICAL.js available on unpkg.

  • Unminified ES6 module:
  • Unminified ES5 version:


The stock ical.js does not register any timezones, due to the additional size it brings. If you'd like to do timezone conversion, and the timezone definitions are not included in the respective ics files, you'll need to use ical.timezones.js or its minified counterpart.

This file is not included in the distribution since it pulls in IANA timezones that might change regularly. See the github actions on building your own timezones during CI, or grab a recent build from main.


For a few guides with code samples, please check out the wiki. If you prefer, full API documentation is available here. If you are missing anything, please don't hesitate to create an issue.


To contribute to ICAL.js you need to set up the development environment. A simple npm install will get you set up. If you would like to help out and would like to discuss any API changes, please feel free to create an issue.


The following test suites are available

npm run test-unit         # Node unit tests
npm run test-acceptance   # Node acceptance tests
npm run test-performance  # Performance comparison tests
npm run test-browser      # Browser unit and acceptance tests

npm run test              # Node unit and acceptance tests (This is fast and covers most aspects)
npm run test-all          # All of the above

See the wiki for more details.

Code coverage is automatically generated for the node unit tests. You can view the coverage results online, or run them locally to make sure new code is covered.


To make sure all ICAL.js code uses a common style, please run the linters using npm run lint. Please make sure you fix any issues shown by this command before sending a pull request.


You can generate the documentation locally, this is also helpful to ensure the jsdoc you have written is valid. To do so, run npm run jsdoc. You will find the output in the docs/api/ subdirectory.


When you are done with your work, you can run npm run build to create the single-file build for use in the browser, including its minified counterpart and the source map.


ical.js is licensed under the Mozilla Public License, version 2.0.