The biggest problem with leave management software is that nobody wants to open another app. Your team already lives in Google Calendar, Outlook, or Apple Calendar. If they have to log into a separate tool to see who's off today, they simply won't. Calendar sync solves this by pushing approved absences directly into the calendars your team already uses, using an open standard called iCal.
Without calendar sync, your team's leave data lives in a silo. The HR system knows that Sarah is off next Thursday, but the project manager scheduling a sprint review doesn't. The result is double-booked meetings, missed deadlines, and frustrated employees who have to explain "I'm on leave that day" three times.
Calendar sync creates a single source of truth. When a leave request is approved, it appears as an all-day event in the calendars people already check every morning. No context-switching, no logging into a second system, no surprises.
The key benefits are:
iCal (formally iCalendar, defined by RFC 5545) is an open standard for exchanging calendar data. It uses .icsfiles that describe events in a structured text format. Every major calendar application supports it — Google Calendar, Microsoft Outlook, Apple Calendar, Thunderbird, and dozens more.
There are two ways to use iCal:
.ics file and import it. This is a one-time snapshot; it doesn't update..ics feed. The calendar app polls this URL periodically (typically every few hours) and updates automatically.For leave management, subscriptions are what you want. When a new absence is approved or a request is cancelled, the feed updates, and your calendar picks up the change on its next refresh.
Good leave management software offers at least two types of calendar feed:
Shows only your own approved leave. Useful for employees who want to see their time off alongside personal events. This feed typically includes the leave type (annual leave, sick leave, TOIL) and the dates.
Shows all approved leave for your team, department, or the entire company. This is what managers care about — seeing at a glance who's off on any given day. Team feeds usually show the employee's name and the leave type.
Some systems also offer department-level feeds so a marketing manager only sees marketing absences, not the entire company.
Calendar subscriptions present a security challenge. When Google Calendar fetches your iCal feed, it can't log in with a username and password — it just sends a plain HTTP GET request to the URL you gave it.
The solution is token-based authentication. Each calendar feed URL contains a unique, random token — something like:
https://app.leaveapprove.com/api/ical/team/abc123def456
This token acts as both the identifier and the password. Anyone with the URL can see the feed, but the token is long enough (typically 32+ characters) that it can't be guessed. If a token is compromised, you regenerate it — the old URL stops working instantly.
The key security principle: no passwords are shared. The token is generated by the system and embedded in the URL. It doesn't grant access to anything else — just the calendar feed.
Google Calendar will fetch the feed immediately and then refresh it roughly every 12–24 hours. You can't control the refresh interval — that's a Google limitation. New leave approved today will typically appear in your Google Calendar by tomorrow.
Outlook typically refreshes subscribed calendars more frequently than Google — roughly every 1–4 hours depending on the client.
Calendar feeds can expose sensitive information if not handled carefully. Consider these points:
LeaveApprove provides iCal calendar feeds for both individuals and teams: