Is there a good app for sync multiple calendars?
Prime Gap: 25 apps already serve this, and 116 data points mined from real user reviews across 4 sources show where they fall short. Heavily used and done badly — the most disruptable kind of gap.
Data refreshed September 7, 2026 · scores recompute weekly as new reviews are mined, so re-check before you build.
What users complain about
The most common complaints behind apps that try to sync multiple calendars, mined and clustered from real reviews:
| Complaint area | Type | Mentions | What a user said |
|---|---|---|---|
| cross-device sync | missing-feature | 5 | que se pueda tener la Opción de Sincronizar entre equipos las notas |
| no Apple Calendar integration | missing-feature | 4 | No Apple Calendar integration in 2026 is insane |
| Google Calendar sync | missing-feature | 2 | it should sync with Google Calendars which is very inefficient for an android app |
| Google Calendar sync drops calendars | reliability | 2 | Googleカレンダーの一部のカレンダーが同期しなくなりました |
| no Google Calendar sync | missing-feature | 2 | syncing Google calendar isn't available either |
| Google Calendar sync broken | reliability | 2 | googleカレンダーへの同期も2月ぐらいから出来ていない |
| cloud sync | missing-feature | 2 | Sincronização na nuvem |
| PC sync | missing-feature | 2 | Mir fehlt eigentlich nur eine Möglichkeit zur Synchronisation mit dem PC |
| calendar sync with other calendars | bug | 1 | Der Kalender lässt sich nicht mit anderen Kalender synchronisieren |
| calendar synchronization | missing-feature | 1 | I wish it synced with your calendars |
| calendar sync with external calendars | missing-feature | 1 | calendar Synchronization with Apple, Google, and Outlook Calendars |
| cross-device calendar sync | bug | 1 | lässt sich der Kalender nicht mehr mit Kalendern auf anderen Geräten synchronisieren |
Apps that already serve this
| App | Rating | Ratings | Price |
|---|---|---|---|
| Calendar | 4.9 | 1,514,776 | Free |
| TimeTree: Shared Calendar | 4.9 | 91,160 | Free |
| Awesome Calendar | 4.6 | 3,871 | $9.99 |
| gtsync: Sync Tasks & Reminders | 4.8 | 4 | $4.99 |
| Howbout: shared calendar | 4.8 | 49,811 | Free |
| Easy Calendar | 4.7 | 2,595 | $1.99 |
| Calendars: Schedule Planner | 4.7 | 121,591 | Free |
| shift calendar pro | 4.4 | 19 | $1.99 |
Should you build it?
Heavily used and done badly — the most disruptable kind of gap. Opportunity here scores 95 out of 100 — a function of demand, how crowded the field is, and how badly the existing apps perform. Use the live map to compare it against adjacent tasks.
Who has tried building this
8 attempts but half stale and the leader only 183 stars — recurring builds, none sticky, suggesting a thankless maintenance burden.
| Project | Status | Stars | Stack |
|---|---|---|---|
| karbassi/sync-multiple-google-calendars | active | 183 | JavaScript |
| agruen/busybridge | active | 15 | Python |
| regalstreak/multiple-google-calendars-sync | stale | 11 | JavaScript |
| Yodavatar/Harmony | active | 9 | TypeScript |
| agopalareddy/GoogleCalendarSync | active | 8 | JavaScript |
| NSueiro/MultipleCalendarSyncForGoogleHome | stale | 8 | JavaScript |
| David-Engel/OutlookCalendarSync | stale | 7 | C# |
| pauldev20/calendarsync | stale | 7 | Python |
Open-source projects that attempted this task — active ones show today's bar; abandoned ones are a signal to validate why earlier attempts died.
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