Smart-home automations that trigger on time-of-day break the first Tuesday you have an early meeting. Automations that trigger on your calendar don’t. The lights stay off the morning you’re traveling, the heater warms the office an hour before a “focus time” block, and the dog camera goes on when the “at office” event starts.
We tested seven Android apps for tying a calendar to smart-home automations. Some are the smart-home platform itself; some are the calendar layer that makes cross-service events usable; some are the glue between the two. We ran every setup against a home-lab Home Assistant instance and a Nextcloud calendar server for two weeks.
What to look for in a calendar-to-smart-home stack
- Where is the calendar hosted. Google, iCloud, Nextcloud, self-hosted CalDAV — each shapes what the automation layer can see.
- CalDAV vs API. Home Assistant reads CalDAV natively (Nextcloud, Baikal); Google Calendar goes through Google’s API.
- How events map to states. A single “AtOffice” event driving “office lights on” is one shape; keywords in event titles driving different automations is another.
- Offline behavior. If the internet drops, does the automation still fire from the last-known calendar state?
- Multi-user. Family calendars mean multiple people with different automations.
- Privacy. Calendar contents leaking through a smart-home integration is a real concern.
Quick comparison
| App | Best for | Role | Free plan | Local option | Rating |
|---|---|---|---|---|---|
| Home Assistant | The automation engine | Automation | Free (self-hosted) | Yes | 4.6 |
| Nextcloud | Self-hosted calendar source | Calendar server | Free | Yes | 4.4 |
| DAVx5 | Sync CalDAV/CardDAV to Android | Sync layer | Fully free | Yes | 4.6 |
| Google Calendar | Everyday calendar you already use | Calendar client | Free | Cloud | 4.5 |
| IFTTT | No-code Google Calendar triggers | Rule engine | Limited free | Cloud | 4.2 |
| Tasker | On-phone automation | Local rule engine | Around $3.49 one-time | Yes | 4.5 |
| Fossify Calendar | Open-source local calendar | Calendar client | Free, open-source | Yes | 4.6 |
The apps
1. Home Assistant, best automation engine
Home Assistant is the base layer here. Its Calendar integration reads events from CalDAV sources (Nextcloud, Baikal, Radicale), Google Calendar via the Google API integration, iCloud via CalDAV, or Office 365 via its integration. Automations can fire on “calendar event starts,” “calendar event ends,” “event in the next hour,” and match against title keywords.
Home Assistant for calendar-driven automations is the ceiling of this category. Once your calendar is in, “if the next event is ‘Client meeting,’ turn on the office ring light and set Slack to Do Not Disturb” is a five-line automation.
Where it falls short: You’re running a server. Setup is a real hour of work the first time. The Android companion app is polished, but the initial configuration is on the web UI.
Pricing:
- Free, self-hosted
- Nabu Casa Cloud around $6.50/mo for remote access (optional)
Platforms: Android, iOS, Web
Download: Aptoide · Google Play · App Store
Bottom line: The right pick as the automation engine. Every other entry on this list serves it or supplements it.
2. Nextcloud, best self-hosted calendar source
Nextcloud is the calendar server that hands Home Assistant clean CalDAV data without going through Google. Nextcloud Calendar is a real CalDAV endpoint; Home Assistant’s Nextcloud (or generic CalDAV) integration reads events directly.
Nextcloud for calendar-driven automations is the “no third-party cloud in my automations” pick. Family shares work; per-user calendars are read separately by Home Assistant.
Where it falls short: You’re running another server. Nextcloud is fine on a Pi 4 or an old mini-PC but adds one more thing to maintain.
Pricing:
- Free, self-hosted
- Nextcloud-managed hosting available for a modest monthly fee
Platforms: Android, iOS, Web
Download: Aptoide · Google Play · App Store
Bottom line: The right pick when the calendar should live on your hardware.
3. DAVx5, best sync CalDAV/CardDAV to Android
DAVx5 is the Android-side glue that syncs a CalDAV server (Nextcloud, iCloud, Baikal) to Android’s native calendar. Once DAVx5 syncs, Google Calendar, Fossify Calendar, and any other Android calendar app sees the events. Home Assistant then reads them the same way from the server side.
DAVx5 for calendar-driven automations is what makes a self-hosted calendar practical on your phone. Add-account, put in the URL, sync, done.
Where it falls short: Adds a small step to setup. Sync intervals default to something conservative; you’ll want to tune them.
Pricing:
- Free from F-Droid
- Small paid version on Google Play to support development
Platforms: Android
Download: Aptoide · Google Play · F-Droid
Bottom line: The right pick as the sync layer. Install first if you’re leaving Google Calendar.
4. Google Calendar, best everyday calendar you already use
Google Calendar is where most calendars actually live. Home Assistant’s Google Calendar integration reads it (with a fair amount of OAuth setup) and hands the events to automations. If you don’t want to run Nextcloud, this is the shortcut.
Google Calendar for calendar-driven automations is the “already have it, use it now” answer. Real-time trigger fidelity is good; the OAuth token needs occasional refresh.
Where it falls short: Cloud-hosted, so Google sees whatever events you route through the integration. OAuth quota limits apply.
Pricing:
- Free
Platforms: Android, iOS, Web
Download: Aptoide · Google Play · App Store
Bottom line: The right pick when the calendar is already Google’s and you want the shortest path.
5. IFTTT, best no-code Google Calendar triggers
IFTTT hooks Google Calendar events to smart-home services (Philips Hue, LIFX, Nest, Wyze, and dozens more) without writing YAML. “If a Google Calendar event contains ‘Meeting,’ then set Hue lights to focus.” Fast to set up; friction-free for people who don’t want a Home Assistant server.
IFTTT for calendar-driven automations is the low-effort route. Works even if you don’t have a smart-home hub, as long as the target service has an IFTTT applet.
Where it falls short: The free tier caps applets. Trigger latency runs anywhere from a few seconds to a few minutes; not for tight timing. Your data flows through IFTTT’s servers.
Pricing:
- Limited free tier
- Around $3.99/mo Pro
- Higher tier for unlimited applets
Platforms: Android, iOS
Download: Aptoide · Google Play · App Store
Bottom line: The right pick when the automations are simple and you don’t want a server.
6. Tasker, best on-phone automation
Tasker is the veteran Android automation app that reads local calendar events (any calendar Android knows about) and triggers phone-side or network actions. Send an HTTP POST to Home Assistant, change your phone profile, turn on Do Not Disturb, or fire off any webhook a smart device accepts.
Tasker for calendar-driven automations is the “one app on the phone does it all” pick. Pair with DAVx5 for a fully self-hosted calendar + local automation stack that survives your Wi-Fi going down.
Where it falls short: Tasker’s learning curve is legitimate; the UI is dense. Expect one or two evenings before your first serious automation ships.
Pricing:
- Around $3.49 one-time on Play Store
- Free trial via download from the developer
Platforms: Android
Download: Aptoide · Google Play
Bottom line: The right pick when the automation should run on the phone even if the server is down.
7. Fossify Calendar, best open-source local calendar
Fossify Calendar is the community-maintained fork of the beloved Simple Calendar. Fully local, no accounts, no telemetry. Pair with DAVx5 to sync a Nextcloud CalDAV calendar into it, and Android sees the events natively.
Fossify Calendar for calendar-driven automations is the “clean, private calendar client” front-end. It doesn’t drive automations itself; it makes the calendar work well on the phone.
Where it falls short: Not an automation tool. You’re pairing it with Home Assistant (via CalDAV on the server) or Tasker (via Android’s shared calendar).
Pricing:
- Free, open-source (GPL)
Platforms: Android
Download: Aptoide · Google Play · F-Droid
Bottom line: The right pick as the calendar client when everything else is self-hosted.
How to pick
The simplest stack: Google Calendar + IFTTT + your smart plugs and lights. No server, quick setup, coarse timing.
The recommended stack: Home Assistant + Nextcloud + DAVx5 on your phone. Real timing, real control, no third-party cloud in the loop.
The tightest local stack: Nextcloud + DAVx5 + Tasker. Everything runs on your hardware; even the internet dropping doesn’t stop the automations from firing.
The middle path: Home Assistant + Google Calendar. Keep the calendar where you’re already using it, add the automation engine.
Add Fossify Calendar as the phone-side client whenever the goal is to move off Google’s calendar app.
FAQ
Can Home Assistant read Google Calendar? Yes, via the official Google Calendar integration. It uses OAuth and reads events for automation triggers.
Is DAVx5 free? Yes on F-Droid. The Play Store version is a small paid download to support development.
Do calendar-driven automations work offline? Home Assistant caches the next window of events, so short internet outages don’t break automations that were already scheduled. Tasker running from the phone’s local calendar keeps working entirely offline. IFTTT and cloud-only integrations do not.
Which app has the smallest privacy footprint? Home Assistant + Nextcloud + DAVx5 + Fossify Calendar is the setup with no third-party cloud involvement. Everything runs on your hardware.
Can I make automations fire on event title keywords? Yes in Home Assistant (filter by summary regex) and yes in Tasker (calendar event contains). IFTTT applets can trigger on “any event” or “event title contains a phrase.”
What if I don’t want to run a server? Use Google Calendar + IFTTT. Pair with cloud-connected smart plugs and lights. It’s the shortest path, at the cost of cloud dependency and coarser timing.