How Musubi compares.
An honest look at how Musubi stacks up against the apps that do a similar job — private shared calendars for the people you plan with. Google, Apple and Outlook aren’t rivals here; they’re the calendars these apps plug into, so they sit in the “what it can sync” rows below.
Feature by feature.
| Musubi | TimeTree | Cupla | Howbout | Self-hosted CalDAV | |
|---|---|---|---|---|---|
| iPhone + Android apps | Android nowiOS in testing | Yes | Yes | Yes | Via CalDAV apps |
| Two-way sync with your existing calendars | |||||
| Google Calendar | Two-way | View only | Two-way | View only | No |
| Apple / iCloud | Two-way | No | Two-way | View only | No |
| Outlook / Microsoft 365 | Two-way | No | Two-way | View only | No |
| CalDAV (Nextcloud, Fastmail…) | Two-way | No | No | No | Native |
| Sharing, privacy & openness | |||||
| Private invite-only sharing | Yesowner / editor / viewer | Yes | Two people | Yes | Manual |
| Ad-free & no data sold | Yes | Ads on free tier | Yes | Freemium | Yes |
| Open source | Yes (MIT) | No | No | No | Yes |
| Self-hostable | Yes | No | No | No | Yes |
| Cost | |||||
| Price | Free (beta) | Free / $4.49·mo | Free / ~$4.99·mo | Free / Howbout+ | Free (self-host) |
Last checked July 2026. App features and pricing change and vary by region — check each vendor’s site for current details.
The alternatives, fairly.
TimeTree
A genuinely good free shared calendar with per-event chat and photos — a long-time favourite for couples and families. Two catches: it’s its own calendar rather than a two-way sync of the one you already use (it can display Google read-only), and the free tier shows ads. Musubi syncs your existing calendars both ways and stays ad-free.
Cupla
Polished and couples-focused, with real two-way sync to Google, Apple and Outlook plus shared lists — the closest to Musubi on sync. The differences: Cupla is built for two people, closed source, and gates features behind a subscription. Musubi works for any small group, adds owner/editor/viewer roles and CalDAV, and is open source and self-hostable.
Howbout
A big, well-made shared calendar for friends and groups (8M+ users), with a chat per plan. It pulls your Google, Apple and Outlook calendars in so nothing clashes — but that’s a read-in view for planning, not a two-way sync back to your calendars, and it’s closed source. Musubi writes changes back both ways and you can host it yourself.
Cozi
The long-standing family organiser — shared calendar plus shopping and to-do lists. Great for household logistics, but it’s its own calendar (no two-way Google sync), ad-supported on the now-limited free tier, and closed source. Musubi is the pick if you want your real calendars synced and no ads.
Self-hosted CalDAV (Nextcloud, Radicale)
Maximum control and fully open source — you already own the data. What they don’t give you is a polished sharing experience; they’re a protocol plus generic clients, and they don’t sync Google/Outlook for you. Musubi adds invite-only sharing, roles and a real app on top, syncs the big providers — and is itself self-hostable.
Where Musubi lands.
If you want the calendars you already use — Google, Apple, Outlook or CalDAV, across iPhone and Android — tied into one view you share only with a chosen few, without ads or a social layer, Musubi is built for exactly that. It’s open source and self-hostable if you’d rather run it yourself.