Connect Cal.com and Slack

Cal.com fills your calendar, and your team wants to know who is coming and who dropped out. FlowMattic posts Cal.com bookings, cancellations and reschedules to Slack, sends each host their own changes and reminds them to follow up when a meeting ends. Sales, success and consulting teams keep an eye on the week from team chat.

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4 triggers 14 actions 6 example workflows 2 ready-made templates Unlimited runs

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When this happens in Cal.com4 triggers

Do this in Slack14 actions

1. TriggerBooking Cancelled

2. ActionSend Channel Message

When Cal.com fires Booking Cancelled, FlowMattic runs Send Channel Message in Slack with the data from that event.

You build this in the FlowMattic workflow builder on your own site. See the setup steps

Cal.com and Slack workflows you can build

Each one uses only triggers and actions the two integrations ship today, plus FlowMattic's own tools. Where the library has a ready-made template, import it instead of building from scratch.

Ready-made template

Post cancelled Cal.com bookings to Slack

A cancellation frees a slot and may mean a lost deal. The team sees who cancelled and the reason they gave, and can reach out to rebook.

Booking CancelledSend Channel Message

View the template

Share new bookings with the time in your zone

Date/Time Formatter turns the start time into your team's local date and hour, so the bookings channel shows when the meeting really is for the people reading it.

Booking CreatedDate/Time FormatterSend Channel Message

Tell the host directly when a meeting is moved

The host is found in Slack by their email and gets a direct message with the new time, so a rescheduled call never surprises them.

Booking RescheduledFind User by EmailSend Direct Message

Remind the host to send notes after a meeting

Meeting Ended fires after the call. Slack adds a reminder for the host to send the recap and next steps while the conversation is fresh.

Meeting EndedFind User by EmailAdd Reminder

Route bookings to a channel per event type

A Router reads the event type. Demo bookings go to sales, onboarding calls to customer success and support sessions to the support channel.

Booking CreatedRouterSend Channel Message

Open a deal channel for enterprise demo bookings

A Filter passes only your enterprise demo event type. Slack creates a channel for the prospect and invites the account executive, so prep starts before the call.

Booking CreatedFilterCreate ChannelInvite User To Channel

Set up: cancellations to Slack

At the end, every Cal.com booking that is cancelled is posted to your team channel with the attendee, time and reason.

Connect Slack
Under Connects in FlowMattic, add a Slack connection with an account in the channel you want to use.
Start with Booking Cancelled
Create a workflow with the Cal.com Booking Cancelled trigger and follow its instructions to add the workflow's webhook in Cal.com.
Cancel a test booking
Book one of your event types yourself and cancel it, so FlowMattic captures the booking fields.
Post the cancellation
Add Send Channel Message, choose the channel and write the text from the attendee, event type, start time and reason. Test it and switch on.

Import the ready-made template Beginner, about 5 min to set up

Slack app icon — Built on the FlowMattic canvas. Test each step with real data, then switch the workflow on.

From Cal.com	To Slack
Attendee name	Message: who
Attendee email	Message: email
Event type	Message: meeting
Start time	Message: was booked for
Cancellation reason	Message: reason

Triggers and actions in this pair

A trigger starts a workflow. An action is something FlowMattic does in the app as a step.

Good to know

Cal.com sends times in a standard format with a time zone. Use Date/Time Formatter so Slack shows the time your team works in.
Webhooks in Cal.com can be set for your whole account or a single event type. Pick the scope that matches which bookings should reach Slack.
Booking Rescheduled is a separate trigger from Booking Cancelled. Set up both if the team should hear about moved meetings as well as dropped ones.

Cal.com

Integration page

Triggers (4)

Booking CreatedTriggers when a booking is created.
Booking CancelledTriggers when a booking is cancelled.
Booking RescheduledTriggers when a booking is rescheduled.
Meeting EndedTriggers after meeting ends.

Slack

Integration page

Actions (14)

Send Channel MessagePost or Schedule a new message to a specific #channel
Add ReminderAdds a reminder for the user
Create ChannelCreates a new channel
List All ChannelsRetrieve list of all channels
Set Channel TopicSets the topic on a selected channel
Set StatusSets your Slack status to the given text and emoji
Invite User To ChannelInvite an existing User to an existing Channel. You must be a member of the channel to invite someone to it
Find User by EmailFinds a user by matching against their email instead of their username
Find User by IDFinds a user by their ID.
Send Direct MessageSend a direct message to a user or yourself from the Slackbot. Can also schedule a message for later
Send Private Channel MessagePost a new message to a private channel you choose. Can also schedule a message for later
Update ProfileUpdate basic profile fields such as name or title
Find MessageFinds a Slack message using the Slack Search feature
Upload FileUpload file to your slack workplace

Why run this pair with FlowMattic

Cal.com and Slack connect through FlowMattic on your own site, with no separate automation account in the middle and no charge per run.

Hosts hear about their own changes

Direct messages for reschedules and follow-up reminders reach the person who owns the meeting, not just a shared channel.

Cancellations get a reply

The team sees a cancelled demo or consultation quickly and can offer a new time before the prospect moves on.

Busy calendars cost nothing extra

FlowMattic runs on your own WordPress site with unlimited runs, so a full week of meetings does not change your bill.

Common questions

How do I connect Cal.com to Slack?

Add a Slack connection in FlowMattic, create a workflow with a Cal.com trigger such as Booking Created or Booking Cancelled and add its webhook in Cal.com. Then add Send Channel Message, map the attendee and time and switch it on.

Can each host get their own bookings in Slack?

Yes. Use the organiser's email from the booking with Find User by Email, then Send Direct Message. Each host only sees the bookings they are hosting.

Can I post a reminder before the meeting starts?

Yes. Use Send Channel Message, which can schedule a message for later, or Add Reminder with a time based on the booking's start time.

Does it work with self-hosted Cal.com?

The trigger works through webhooks. If your self-hosted Cal.com can send webhooks to your WordPress site, the same workflows apply.

Did not find your answer? You can browse the help center or ask us directly.

Start automating Cal.com and Slack

Install FlowMattic, connect both accounts and import a template. Every run stays on your own server.

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Reviewed 27 Oct 2026. The example workflows are written with AI from the real triggers and actions of both integrations and checked against them. Cal.com integration 1.0.0, Slack integration 1.0.