ShadowCal only goes Outlook → Google. CalendarPipe works every direction.
ShadowCal copies Outlook events into Google as shadow events using an Outlook publish link. CalendarPipe connects Google, Outlook, and Apple as first-class sources and targets, then lets you filter and transform what syncs with programmable rules.
- Free forever plan
- 14-day Pro trial
- No credit card to start
- 2 min setup
Where ShadowCal falls short
ShadowCalhas strengths, but here's what users run into.
One direction, two providers
ShadowCal is built for Outlook → Google only. You cannot sync Google into Outlook, include Apple / iCloud, or route events between other combinations.
Publish-link plumbing, not full OAuth sync
ShadowCal reads Outlook through a calendar publish link and writes shadow events into Google. That is fine for a simple mirror, but you do not get two-way sync, invitation delivery, or richer event control.
No rules beyond copy-as-shadow
Every Outlook event becomes a Google shadow event. You cannot filter by keyword, strip details selectively with code, skip weekends, or transform titles before they land.
No API or agent tooling
ShadowCal is a finished consumer sync. There is no REST API, no webhooks for your automations, and nothing for AI agents to drive calendars programmatically.
Why teams switch to CalendarPipe
Any direction, not one path
Connect Google, Outlook, and Apple as sources or targets. CalendarPipe is not locked to a single Outlook→Google mirror.
Decide what crosses the boundary
Write JavaScript gate functions, use the visual builder, or describe a rule in plain English. Filter, rewrite, and strip details before events land on the destination.
Free forever when needs are light
CalendarPipe's free plan never expires — 2 calendars, 1 sync rule. Upgrade to Pro only when you need unlimited rules and faster sync.
Built for developers and agents
A REST API and an MCP server for AI agents. Host calendars an agent owns, or wire sync into your own workflows.
Feature comparison
CalendarPipe vs ShadowCal — side by side.
| Feature | CalendarPipe | ShadowCal |
|---|---|---|
| Google Calendar | Yes | Yes |
| Outlook / Microsoft 365 | Yes | Source only (publish link) |
| Apple Calendar / iCloud | Yes | No |
| ICS / internet calendar feeds | Yes | Outlook publish link |
| Two-way / multi-direction sync | Yes | No |
| Programmable sync rules (JavaScript) | Yes | No |
| Event filtering & transformation | Full (JS sandbox) | Mirror as shadow |
| Invitation-based delivery | Yes | No |
| REST API | Yes | No |
| MCP server for AI agents | Yes | No |
| Sync frequency | Every 15 min (Free) / 5 min (Pro) | ~1 minute |
When ShadowCal is the better choice
We'd rather you pick the right tool than the one we sell.
You need near-instant mirroring
ShadowCal polls about every minute. CalendarPipe syncs every 15 minutes on Free and every 5 minutes on Pro. If an Outlook change has to appear in Google within a minute, ShadowCal is faster and CalendarPipe is not.
You cannot OAuth your work Outlook
ShadowCal reads Outlook through a calendar publish link rather than an OAuth connection. If your employer will not approve a third-party app on the work tenant, a publish link may be the only route you have — CalendarPipe connects Microsoft 365 with OAuth.
One-way Outlook → Google is the whole job
ShadowCal does exactly that and nothing else. If you never need Apple Calendar, other directions, or filtering, a narrower tool is less to configure and less to get wrong.
Switching from ShadowCal is low-risk
There's no data to move and no hard cutover. Run CalendarPipe alongside ShadowCal, then switch over only once you're ready.
- 1
Run both while you test
CalendarPipe and ShadowCal do not conflict. Keep ShadowCal running until you confirm CalendarPipe covers the calendars and directions you need.
- 2
Nothing to export
There is no data migration. CalendarPipe reads from the calendars you connect; you recreate sync rules rather than moving events.
- 3
Live in about two minutes
Connect Google and Outlook (and Apple if you need it), pick a template or describe a rule, and cancel ShadowCal once you are happy.
Frequently asked questions
Common questions about switching from ShadowCal.
Is CalendarPipe a replacement for ShadowCal?
Does CalendarPipe sync as fast as ShadowCal?
Can CalendarPipe sync Outlook without a publish link?
Does CalendarPipe create “shadow” busy blocks?
Ready to switch from ShadowCal?
Two minutes to set up. Free forever plan, no credit card. Or try Pro free for 14 days.