OneCal vs CalendarSync
Unlike most comparisons, this one is written by a direct competitor. Here is an honest, specific breakdown of what each tool does best and where the real differences are.
Last updated . Checked on against each product’s public website. Plans and prices change, so confirm on their site before you buy.
The Short Version
OneCal and CalendarSync are two of the most directly comparable multi-calendar sync tools in 2026. Both connect Google Calendar, Outlook and Apple Calendar (iCloud), both handle two-way sync with per-sync privacy settings, both have booking pages, and both list an MCP server for AI assistants. The differences are price, apps and developer access. CalendarSync Pro covers unlimited calendars for SGD 7 a month (SGD 60 a year), includes a REST API, and sets Blocker or Mirror mode on each sync pair. OneCal prices per user by calendar count, from US$5 a month billed yearly for 2 calendars, and lists native iOS, Android and macOS apps and a user provisioning API. If you need more than 2 calendars or programmatic control, CalendarSync is the better value. If native apps or team provisioning matter more, OneCal is.
CalendarSync vs OneCal: Feature by Feature
| Feature | CalendarSync | OneCal | Winner |
|---|---|---|---|
| Google Calendar support | First-class (OAuth + webhooks) | First-class | |
| Outlook / Microsoft 365 support | First-class (Microsoft Graph webhooks) | First-class | |
| Apple / iCloud Calendar (CalDAV) | Yes, via CalDAV (iCloud)Step-by-step Apple Calendar guide (about 3 minutes) | Yes (iCloud) | |
| Real-time sync speed | Near-instant on Google and Outlook; Apple every minute on Pro | Described by OneCal as real-time on Google, Outlook and iCloud | |
| Privacy per sync (busy only or full details) | Blocker or Mirror, set on each sync pair | Yes. Every plan lets you choose what event information each sync copies | |
| Booking page | Yes, simple | Yes | |
| REST API for developers | Yes, on Pro plan | Not listed (plans list a user provisioning API and Zapier) | |
| MCP server for AI agents | Yes, on Pro | Yes, on every plan | |
| Native mobile and desktop apps | No. Runs in your browser | iOS, Android and macOS apps on every plan | |
| Calendars included | Unlimited on Pro (2 on the Free plan) | 2, 5 or 50, by plan | |
| Pricing (checked September 2026) | Free plan, or Pro at SGD 7 a month (SGD 60 a year) per account | US$5 to US$25 per user a month, billed yearly, after a 14-day trial |
When CalendarSync Wins
- You need more than 2 calendars: CalendarSync Pro covers unlimited calendars for SGD 60 a year, where OneCal's US$60-a-year plan covers 2
- You need a REST API to check sync status, list your pairs and trigger a sync from your own code
- You want a free plan to start: CalendarSync Free keeps 2 calendars in sync with one one-way pair
- You want one flat price per account as you add client calendars
When OneCal Wins
- You want native iOS, Android and macOS apps
- You are rolling sync out to a team and want a user provisioning API and a Zapier integration
- You prefer a more established brand with a longer track record
- You want a tool with an existing community and support history
Our Recommendation by Use Case
User who wants native mobile and desktop apps
Pick: OneCalOneCal lists iOS, Android and macOS apps on every plan. CalendarSync runs in your browser, so there is nothing to install, but there is no app either.
Freelancer or consultant with mixed-provider client calendars
Pick: CalendarSyncClient work quickly passes 2 calendars, and each new client adds one. CalendarSync Pro covers unlimited calendars for SGD 7 a month, and you set Blocker or Mirror on each pair so every client boundary gets the privacy it needs. OneCal prices by calendar count, from 2 calendars on Starter to 50 on Premium (US$25 a month, billed yearly).
Developer or team that wants to integrate calendar sync into a custom workflow
Pick: CalendarSyncCalendarSync Pro includes a REST API with key-based auth. Check sync status, list connections and pairs, trigger a sync, and read or update meetings from your own code. OneCal's plans list an MCP server, a user provisioning API and Zapier; we found no public API for triggering syncs.
Company rolling sync out to 5+ people
Pick: OneCalCalendarSync is priced and set up one account at a time. OneCal lists a user provisioning API and Zapier on every plan, which suits an admin rolling sync out across a team.
Frequently Asked Questions
Is CalendarSync a better OneCal alternative?
It depends on what you need. Both sync Google, Outlook and iCloud with per-sync privacy settings. CalendarSync costs less once you need more than 2 calendars and adds a REST API. OneCal has native mobile and desktop apps and a user provisioning API for teams.
Does OneCal support Apple Calendar or iCloud?
Yes. OneCal lists iCloud alongside Google and Outlook, so both tools can sync an Apple calendar. CalendarSync connects iCloud over CalDAV with an app-specific password and checks it for changes every minute on Pro, because Apple doesn't notify other apps of changes. The real differences are elsewhere: price per calendar, CalendarSync's REST API, and OneCal's native apps.
Does CalendarSync have a REST API? Does OneCal?
CalendarSync Pro has a REST API: check sync status, list connections and sync pairs, and trigger a sync from your own code, which is useful for developers integrating calendar sync into custom workflows. OneCal's plans list a user provisioning API, a Zapier integration and an MCP server; we found no public API for triggering syncs.
How do the two tools compare on sync speed?
CalendarSync uses Google and Microsoft push notifications, so changes on those calendars usually sync within seconds on Pro and during the trial (every 15 minutes on the Free plan). OneCal describes its sync of Google, Outlook and iCloud as real-time. Apple doesn't notify other apps of changes, so CalendarSync checks Apple every minute on Pro.
Is there a price difference worth caring about?
CalendarSync Pro is SGD 7 a month or SGD 60 a year per account, with unlimited calendars and sync pairs. OneCal prices per user, from US$5 a month billed yearly for 2 calendars up to US$25 a month for 50 calendars. If you need more than 2 calendars, CalendarSync costs less.
Try CalendarSync free for 7 days
Works with Google Calendar, Outlook and Apple Calendar. No credit card required.