The terms for using OpenCalendar.

Last updated 5 October 2026

OpenCalendar is free, needs no account, and keeps your calendar in your own browser. These terms cover the app, the relay and helper it uses by default, the optional account, and this website. By using any of them you agree to these terms.

Who provides it

“We” and “us” mean the operator of this website and of the relay and helper the app uses by default.

What you are using

• The app, at opencalendar.me/app: a calendar and scheduling program that runs in your browser.
• The relay the app uses unless you set another: a server that stores and forwards encrypted records for scheduling links, bookings, polls and shared calendars.
• The helper: a server that fetches calendar addresses a web page cannot read, and completes a Google sign-in. It keeps nothing.
• The account, if you choose to sign in to it: one sign-in shared by our apps, kept by our account server. See The optional account and credits.
• This website.

There is no subscription and no charge for anything in OpenCalendar, and nothing in it needs an account. What each of these does with data is set out in the privacy policy, which is part of these terms.

The optional account and credits

• You do not need it. Every part of OpenCalendar works without signing in, and signing in unlocks nothing in it.
• It is shared. The account is the same one our other apps use, so signing in here signs you in to the same account as signing in there.
• You sign in through a provider you choose (for example Google, OpenWallet ID, a crypto wallet or a Nostr key). You are responsible for keeping that sign-in safe; whoever can sign in with it can use the account.
• Credits are for our other apps. The account page lets you buy credits. Nothing in OpenCalendar costs credits, so do not buy them for OpenCalendar. What credits buy, and on what terms, is set out by the app that spends them.
• You can delete it. “Delete account…” on the account page removes the account and what our account server holds with it. Credits left in a deleted account are lost.

The software is open source

The app, the command-line tool and the helper are licensed under the MIT licence or the Apache License 2.0, at your choice. Those licences, not these terms, govern your right to copy, change and redistribute the code, and you may run your own copy, your own relay and your own helper. These terms cover your use of the copies we host.

Your content and your key

• Your content is yours. Your calendars, events, links and bookings stay in your browser or are stored encrypted, and we claim no rights in them.
• You are responsible for your key and your backups. Your data and your key live in your browser. If you clear the site’s data, lose the device or lose the key, we cannot restore them, because we never had them. Export your calendars and save an encrypted backup of your key.
• You are responsible for the links you hand out. Anyone who holds a scheduling link can read that link’s page and your busy times, and can book. Change the link if it reaches someone it should not.
• You are responsible for your guests’ details. When someone books with you, their name, email address and answers are delivered to you. Handle them as the law where you are requires.

Acceptable use

You agree not to:

• use OpenCalendar to break the law, or to harass, deceive or send unwanted messages to anyone;
• flood a scheduling link, the relay or the helper with requests, or try to get round their limits;
• use the relay to store anything other than what the app and its command-line tool publish;
• use the helper to fetch anything other than a calendar you are entitled to read;
• attempt to break the encryption of, or gain access to, records that are not yours;
• present a scheduling link as coming from someone it does not come from.

The relay limits how much one key may store and how fast one key or address may write. We may refuse, limit or remove records and connections that break these terms or put the service at risk.

Other companies’ services

If you connect a Google or Microsoft account, sign in to the optional account through a provider, pay a payment provider for credits, follow a calendar hosted elsewhere, or paste a Zoom, Google Meet, Microsoft Teams or Tencent Meeting link, you are also using that company’s service under its own terms. We are not responsible for those services, for their availability, or for changes they make. OpenCalendar is not affiliated with, or endorsed by, any of them; their names are their owners’ trademarks.

Availability and changes

We provide the hosted app, relay and helper free of charge and without a promise that they will always be available. We may change, limit or stop any of them. Because the app keeps your data in your browser and exports standard calendar files, and because the software is open source, you can keep using a copy of your own.

Some things described on this site are marked as not yet available. Until that mark is removed they are not part of the service.

Times, time zones and bookings

The app works out times from the time-zone rules built into it, and offers slots from the busy times a host last published. Time-zone rules can change at short notice, and a host’s calendar can change after their busy times were published; the app shows how old those busy times are. Check any time that matters, and do not rely on OpenCalendar alone where a missed or mistimed meeting would cause serious harm.

No warranty

OpenCalendar is provided “as is” and “as available”, without warranties of any kind, whether express or implied, including fitness for a particular purpose and non-infringement, to the fullest extent the law allows.

Limit of liability

To the fullest extent the law allows, we are not liable for indirect, incidental, special or consequential loss, or for lost data, lost profit or missed appointments, arising from your use of OpenCalendar. Nothing in these terms limits liability that cannot be limited by law.

Changes to these terms

If these terms change, the date at the top of the page changes with them. Using OpenCalendar after a change means you accept the new terms.

Contact

There is no contact address yet. The support page will show one when there is, and has help for using the app until then.