So far Kalender Sync has moved events between your own calendars. Starting today it also works the other way round: with Subscribe Calendars you publish events as a calendar other people subscribe to in their calendar app. Built for clubs, course providers, schools and platforms that send events to many people. The calendar is filled through a new interface, the Publisher API.
What a subscribe calendar is
A subscribe calendar is an iCalendar feed that someone adds to Apple Calendar, Google Calendar or Outlook once. From then on new events appear there on their own, and changes arrive when the calendar app fetches the feed again. Nobody has to copy single events or read group emails.
For every calendar you get three things:
- A feed on
feeds.kalender-sync.dethat any calendar app can read. - A subscribe page with your logo, banner, organizer and upcoming events. The menu leads straight to Apple Calendar, Google Calendar, Microsoft 365, Outlook.com and Outlook (desktop). Any other app gets the feed link to copy. Sharing works via social links, a QR code or the device’s share menu.
- A button for your website that opens the same menu.
This is the button in HTML:
<div class="ks-subscribe" data-calendar="cal_XXXXXXXXXXXX"></div>
<script src="https://app.kalender-sync.de/embed/v1/button.js" async></script>Set language, color and label with data-lang, data-color and data-label. The button renders in a Shadow DOM, so your site’s CSS cannot break it.
No trackers, no cookie banner
The subscribe page and button load only from our own domain and set no cookies. We do not store who subscribes: no IP address, no user agent. The “you already subscribed” note lives only in the visitor’s browser. Kalender Sync is a German company hosting in Germany, and event content is stored encrypted in the database.
You still get numbers: the stats show active subscribers per calendar app and clicks on the subscribe button in the last 30 days. If you want clicks in your own analytics, the button fires a ks:subscribe event with the calendar and the chosen app on every click. You handle it on your own site, under your own consent.
Who it is for
- Clubs: training, match days and meetings, one calendar per team.
- Course providers: a schedule to subscribe to, while booking stays in your own system.
- Schools: parent evenings, holidays and school fairs for parents.
- WordPress sites: events from WordPress, keyed by post ID.
- Platforms and plugins that want to offer subscribable calendars to their users without hosting feeds themselves.
How events get into the calendar
Through the Publisher API, a REST interface at api.kalender-sync.de/v1, publicly described as OpenAPI 3.1. The key points:
- Create or update events by your own ID, for example the WordPress post ID or the course ID from your software. Unchanged events are detected.
- Batch: up to 100 changes in one request.
- Full sync: write all current events, complete the sync, and the calendar removes whatever was not included. If more than half would be deleted, the API asks first.
- Recurrence as a rule with exceptions and modified single dates, so weekly training with a holiday break works.
- Branding per calendar: logo, banner, brand color, organizer and whether events are visible on the subscribe page.
You create the key in the app under Settings. A free account gives you a sandbox key to try everything with up to 3 test calendars. Documentation lives at docs.kalender-sync.de/en/abo-kalender/ for organizers and docs.kalender-sync.de/en/api/ for developers.
Not a developer? An AI assistant like Claude or ChatGPT can write the code for your website from the OpenAPI description or add the button for you.
Pricing
| Plan | Subscribe Calendars |
|---|---|
| Free | Sandbox: up to 3 test calendars, not public |
| Basic (€5 a month) | 1 live calendar, up to 500 active subscribers |
| Professional (€12 a month) | 10 live calendars, up to 5,000 active subscribers |
| Above that | on request |
A subscription counts as active when its calendar app fetched the feed in the last 14 days. Each live calendar holds up to 5,000 events. If a calendar reaches its limit, everything keeps running: you get an email and a note in the stats.
What Subscribe Calendars do not do
So you can plan honestly:
- No instant updates. Subscribers see changes when their calendar app fetches the feed. Google Calendar often takes several hours, Apple and Outlook vary. That applies to every subscription calendar, not just ours. For a short-notice cancellation, send a message as well.
- No single-event pages and no registrations. You get a subscription to a whole calendar, no add-to-calendar button for single events and no RSVP.
- No embedded calendar view. Your website gets the button; the events are shown on the subscribe page.
- No input form. Events come in via the API, not through a form in the app.
- Subscribe pages are not indexed by search engines.
If you need any of that, AddEvent may be the better fit. The AddEvent vs. Kalender Sync comparison shows who does what better, with sources.
Try it now
- Create a free account.
- Create a sandbox key under Settings.
- Follow the guide in the docs to set up your first calendar and add the button.
Everything about Subscribe Calendars at a glance is on the Subscribe Calendars page. Questions and wishes are welcome at kalender-sync.de/en/contact/.
