Yes, FileMaker can send real calendar invites. Using native script steps available since FileMaker Pro 18, it can build a standard iCalendar (.ics) file and attach it to an email, and most modern calendar apps treat that email as a meeting invitation with accept and decline buttons. The free Calendar Invite Creator add-on gives you a working version you can open and adapt.

Here is the moment it exists for. A site inspection is booked in FileMaker for Thursday at 9 a.m. The inspector hears about it in a forwarded email, types it into his calendar by hand, and gets the time zone wrong. The customer waits on site for an hour. The inspection record had every detail right the whole time. It just had no way to put the meeting on anyone’s calendar.

How do calendar invites work from FileMaker?

Calendar invitations travel as .ics files that follow the iCalendar standard (RFC 5545). When an .ics file is attached to an email, calendar apps such as Outlook, Apple Calendar, and Google Calendar detect it and offer to accept, decline, or tentatively accept the event.

From FileMaker’s side, that is three jobs: assemble the meeting details as iCalendar text, write that text to an .ics file, and attach the file to an email. Because .ics files are plain text, FileMaker’s Data File script steps cover the middle step with nothing extra installed.

What the add-on does out of the box

Open the included KYO_CalendarInviteCreator_Addon.fmp12 file and click Create Add-on to save it as an add-on you can install in your own app. Then enter the meeting details, add attendees and an organizer, and send. The flow behind that button looks like this:

Here is an example of the iCalendar text the add-on produces:

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Meetings_Manager//FileMaker Pro//EN
METHOD:REQUEST
BEGIN:VEVENT
SUMMARY:FileMaker Pro Meeting Invite Creation Demo
UID:4821265E-F188-4A3B-9B47-6B62023885B8@fakemeetingscompany.com
DTSTAMP:20260128T185213Z
DTSTART:20260128T233000Z
DTEND:20260129T000000Z
LOCATION:Online Only
ORGANIZER;CN=Kyo Logic:mailto:kyoLogic@testEmail.test
ATTENDEE;CN=Test Person:mailto:testEmail@testEmail.test
SEQUENCE:2
END:VEVENT
END:VCALENDAR

Every line maps to data that usually already lives in FileMaker: the start and end times, the attendees, and the organizer.

The iCalendar rules that trip people up

The approach is simple. The details are where a proof of concept turns into something you can trust in production.

• Line length. RFC 5545 limits each line to 75 octets. Longer titles and descriptions have to be folded onto continuation lines that start with a space or tab. Folding errors can make an invite get ignored without any error.
• Time zones. Times are usually written in UTC with a trailing Z. Get the conversion wrong and the meeting shows up at the wrong hour for some recipients.
• METHOD. METHOD:REQUEST asks recipients to respond. Without it, some apps simply add the event to the calendar.
• UID and SEQUENCE. Keep the same UID for the life of an event and increase SEQUENCE when it changes. A missing or duplicated UID creates duplicate events instead of updates.

Calendar apps also behave differently, especially desktop versus web calendars. Test with more than one client and with real email addresses before you roll it out.

Where invites from FileMaker earn their keep

• Project and client meetings: every participant gets the same details, tied to the project record.
• Inspections and site visits: field staff get the invite the moment the inspection is assigned.
• Lab or clinic appointments: appointments go out without moving patient or sample data into a third-party scheduler.
• Reviews and approvals: handoffs and audit meetings are scheduled as part of the workflow that needs them.
• Automated follow-ups: a contract approval or a finished milestone triggers the next meeting automatically.

Once basic invites work, the same pattern extends to updates (increase SEQUENCE), multiple attendees, cancellation notices, and logging every invite back to the record. If you want a history of who changed a meeting and when, the Audit Log & Version History add-on covers that side. For a closer look at the file-writing steps themselves, see exporting container data with the Data File script steps.

What this could look like in your solution

The useful version of this is not a button someone remembers to press. It is a meeting invite that goes out because a record reached a certain state: an inspection assigned, an order ready to ship, a review due. The calendar becomes an output of the system instead of a separate chore.

Kyo Logic builds custom Claris FileMaker and manufacturing software for businesses across New England and beyond. If you want help wiring invites into your own scheduling logic, handling time zones for a team spread across regions, or sending updates and cancellations cleanly, reach out.

Frequently asked questions

Can FileMaker send Outlook or Google Calendar invites?

Yes. FileMaker can create a standard iCalendar (.ics) file and email it as an attachment. Outlook, Apple Calendar, and Google Calendar recognize the file as a meeting invitation.

Do I need a plug-in or an outside API?

No. The add-on uses native FileMaker script steps. The Data File script steps that write the .ics file have been available since FileMaker Pro 18.

Why do invites show up at the wrong time?

Usually because of time zone handling. Writing start and end times in UTC with a trailing Z, and converting carefully from local time, avoids most of these problems.

Can I update or cancel an invite I already sent?

Yes. Send a new .ics file with the same UID and a higher SEQUENCE number to update an event. Cancellations follow the same pattern.

Quick takeaways

• Use one UID per event and increase SEQUENCE on every change.
• Write times in UTC and test with at least two calendar apps before rollout.
• Fold any line longer than 75 octets, including long titles and descriptions.
• Download the add-on and send a test invite to yourself before you connect it to real records.