OneCal syncs your Google and Outlook. Your company runs more than that.
OneCal is a solid tool for one person with a few cloud calendars. Companies have Exchange Server in a rack, HCL Domino in a corner, contacts and tasks nobody wants to retype, and an administrator who has to answer for all of it. AddSync Calendar is built for that second case.
Where the two really differ
Three things that decide whether it works for a company.
Systems
AddSync Calendar connects Exchange Server 2016, 2019 and SE, Microsoft 365, Outlook.com, Google, iCloud, HCL Domino, Zoom and CalDAV or WebDAV servers. OneCal lists Google, Outlook, iCloud and CalDAV.
Data
With Silver and Gold, contacts and tasks travel with the calendar where the system supports them. OneCal's pricing page describes calendar sync only.
Control
For Exchange, one service user is enough, so no mailbox passwords are shared. You add people one by one or from a list, and choose the direction per source.
Side by side
What each vendor states publicly. OneCal's side is taken from its pricing page, checked in October 2026.
Who should pick which
It depends on what you run.
AddSync Calendar fits if you
- run Exchange Server, HCL Domino or a mix of systems.
- need contacts or tasks to travel with the calendar.
- want one administrator in control of a whole organisation.
- are in the middle of a migration and need both sides in step.
OneCal fits if you
- are one person or a small team on Google, Outlook and iCloud.
- want to sign up yourself in minutes.
- only need calendar events, nothing else.
- do not need on-premises systems.
Switching is four steps
Connect
Add Exchange, Microsoft 365, Google, iCloud, Domino or a CalDAV server.
Add people
One by one or from a list. They get an email invite and sign in once.
Choose direction
Per source: one way, the other way, or both ways.
Switch the old one off
Check a week of events, then cancel the old tool.
Questions
Is AddSync Calendar a OneCal replacement?
For companies, yes. It covers the same cloud calendars and adds Exchange Server, HCL Domino, contacts and tasks. For one person with two Google calendars, OneCal is probably enough.
Does AddSync sync Exchange Server on premises?
Yes, from the Silver plan. Exchange Server 2016, 2019 and Subscription Edition are supported through one service user.
Where do the OneCal facts come from?
From OneCal's public pricing page, checked in October 2026. Vendors change plans, so check before you decide.
Is there a free trial?
Yes, 14 days.
How is AddSync Calendar priced?
Per account. Basic $3, Silver $5, Gold $8 per account a month, billed yearly ($4, $6 and $10 billed monthly). See the pricing page.
Can I choose which way the data flows?
Yes. For each source you choose one way, the other way, or both ways.
Test it on your own calendars.
Start the 14-day trial, or tell us which systems you run and we will tell you what the sync covers, and what it does not.
