slotmirror

The calendar sync that keeps up with moved meetings.

Move a meeting in one calendar, and its busy copies move in all the others within seconds. Microsoft 365 and Google, self-hosted on Cloudflare.

Deploy to CloudflareView on GitHub

Runs on the Cloudflare Workers free plan · MIT licence

Drag any meeting, orIn sync
 
Work
Client
Private
Click a cell to change what the Work meeting shows there.

A simulation in your browser. No calendar is connected.

How it works

slotmirror runs in your own Cloudflare account. There is no slotmirror service between your calendars and your deployment.

1

Deploy

Deploy the Worker and its database to your Cloudflare account, with the button or with wrangler.

2

Register the apps

Create a Microsoft Entra app and a Google OAuth client, and store them as secrets. The quickstart walks you through it.

3

Connect and choose

Connect your Microsoft and Google accounts. They block each other as busy; add titles or more where you want them.

One page for every direction

Each calendar gets a card: where its events go and how much shows there. The overview on the right shows all directions at once.

The sync editor of slotmirror, with one card per calendar and an overview of all directions
The sync editor, with three demo accounts.

Features

What the editor and the sync do today.

Block group

Calendars in the group see each other as busy, with exceptions.

Detail per direction

Not, busy, title, or everything, with a preview of the copy.

Extra calendars

Subscriptions such as team fixtures can block your time too.

Push notifications

Changes arrive within seconds; a scheduled check catches the rest.

Organisation limits

Admins cap the detail between work and private calendars.

Activity log

Runs and changes with counts and codes, never event content.

EU data location

The database and the sync can stay in Cloudflare's EU jurisdiction.

Colours

A colour per account in the app, and a colour for the blocks it writes.

Why moved meetings get lost

A recurring meeting moved for one week is an exception to its series. Sync tools that rebuild copies on a schedule can miss it until the next full run.

  • slotmirror reads each occurrence of a series, so a moved one keeps its identity.
  • It changes only what differs: create, update or delete, never a rebuild.
  • Push notifications start the sync when the meeting moves, not minutes later.
  • Event contents are read during a sync and kept only in memory, never written to the database.

Guides

Sync Outlook and Google CalendarBusy blocks or titles, in both directions.Show your private calendar as busy at workBlock the time without showing what it is.Sync calendars across Microsoft 365 tenantsTwo companies, or client tenants.Block time for a team or club scheduleA subscribed calendar becomes busy blocks.

Changelog

No release yet.All releases