Calendar events that travel freely across services — like Mastodon, but for events. Publish your calendar once, federate everywhere, subscribe from any client.
No platform lock-in. No vendor account. Your calendar server speaks ActivityPub — the same open protocol powering Mastodon, Pixelfed, and PeerTube.
Run a cal.pub instance (WordPress plugin, self-hosted server, or managed). Your events are published as ActivityPub objects and exposed as a .ics feed simultaneously. One publish, two protocols — works with every calendar app.
When you post an event, your instance sends it to follower inboxes across the network. Anyone who follows @yoga@schwitzkasten.cal.pub on any instance — or in their Mastodon client — gets the event in their feed. WebFinger discovery makes addressing seamless.
Subscribers import your calendar into any iCal-compatible app. RSVPs flow back through ActivityPub. Public events surface automatically on so.cal.pub, the network's public discovery hub — no account required to browse.
From personal holiday tracking to community event hubs — cal.pub scales from a single calendar to a federated network of thousands.
Publish your public events — concerts, meetups, travels — as a subscribable feed. Friends and followers get updates in their own calendar apps without creating accounts.
Share sprint reviews, demos, and team socials across your organisation. Federate events to partner companies without shared tooling or vendor login.
Yoga studio class schedules, maker space open hours, music venue gigs — publish once, appear in local discovery feeds, let regulars subscribe via any calendar app.
Federated availability pages with RSVP — no Calendly account required. Visitors see your free slots and book via a standard ActivityPub interaction.
cal.pub sits in a broader ecosystem of open infrastructure. Each layer is independent, interoperable, and fully open source.
Browse 10,700+ open source projects across self-hosting, infrastructure, productivity and more. Find FOSS alternatives, deployment templates, and the building blocks that power cal.pub itself.
foss.systems →Find calendar apps that speak cal.pub and ActivityPub — desktop, mobile, and web clients, booking plugins, and integration tools. The curator's guide to the open calendar ecosystem.
calendar.solutions →The public flagship instance. Discover events near you, follow community calendars, and see what's happening across the cal.pub network — no account required to browse.
so.cal.pub →A self-registration hub where cal.pub instances announce themselves, aggregate public events, and build a federated directory of every participating calendar across the network.
No proprietary API. No vendor lock-in. cal.pub speaks protocols that already exist — compose, extend, and integrate with the tooling you already use.
W3C recommendation powering the Fediverse. Calendar actors expose Inbox/Outbox endpoints. Events are ActivityStreams 2.0 objects — interoperable with Mastodon, Pixelfed, and any AP-compatible server.
RFC 7033 discovery at .well-known/webfinger. Address any calendar instance with @calendar@domain — resolves across the Fediverse without a central registry.
RFC 5545 iCal export on every instance and calendar actor. Subscribe from Apple Calendar, Google Calendar, Thunderbird, or any .ics-capable client. Recurring events, RSVP PARTSTAT, timezone-aware.
Every event page ships structured data using schema.org/Event vocabulary. SEO-friendly, machine-readable, and compatible with Google's rich event snippets and knowledge graph.
The demo is live. The spec is open. The protocol is yours. No account, no vendor, no lock-in.