Sync booking contacts to Mailchimp or Kit

Both live on the Integrations page, in the sidebar under Insights. Scroll to the last group, Marketing & Analytics, where Mailchimp and Kit (ConvertKit) sit beside the tracking pixels. Each card carries a Connected or Not connected badge and opens a setup panel.

What gets sent to your list

Two things travel with each booking: the email address and the name the client typed on your booking form, plus whichever tags you picked during setup.

The name is split at the first space before it is sent. Mailchimp gets a first and last name — Ada Lovelace arrives as Ada and Lovelace — while Kit takes only the first word.

Nothing else goes across. Not the phone number, not which event type they booked, not the date or time, not their intake answers, not what they paid. This is a contact push and only a contact push.

It is also strictly one-way. Calso never reads back, so connecting does not pull your existing subscribers into your Calso client list — bringing a list into Calso is a separate import — and it gives Calso no ability to send campaigns on your behalf.

Connect your list tool

1. Open the card in Integrations

   Go to Integrations in the sidebar, scroll to Marketing & Analytics, and click Mailchimp or Kit (ConvertKit). The panel that slides out is the whole setup — nothing is configured anywhere else.

2. Paste your API key and press Connect

   The panel tells you where to look: Find your API key in Mailchimp under Account > Extras > API Keys, or Find your API key in Kit under Settings > Advanced > API. Copy the whole key, including the short code after the final dash on a Mailchimp key — that piece tells Calso which Mailchimp server your account lives on. The key is checked with the provider before it saves, so a wrong one comes back as an error under the box rather than a connection that quietly never works.

3. Choose the Audience or Form

   Mailchimp calls the destination an Audience, Kit calls it a Form, and the picker fills itself from your account — choose yours in place of Select audience... or Select form.... If it comes back with No audiences found — verify your API key., the key connected but has no lists behind it, usually because it belongs to a different account than you expected.

4. Press Save Configuration

   A green Saved appears, and a summary panel below reads Syncing to audience — or Syncing to form — with the list name underneath. Until you do this, nothing syncs: a connected key with no audience saved against it pushes nobody.

5. Pick your tags and save again

   Under Tags, click each tag you want applied to people who book, and click a selected one again to drop it — these already exist in your list tool, as Calso creates none. Press Save Configuration a second time.

6. Press Test Connection

   Connection OK means your key is still good. Anything else shows the provider's own message, or Test failed — usually a key that was regenerated or revoked on the other side.

When a contact is pushed

The sync runs once, the moment a client submits your booking form — the same moment the booking appears in your Bookings list.

That is earlier than most people assume. The contact goes out before any payment clears and before you approve anything, so someone who reaches the payment step and walks away — or whose request you later decline — is already on your list.

Only bookings made through your public booking page sync a contact, the embedded version on your own website included, since it runs the same booking flow. Bookings you create yourself from the dashboard, group event enrolments, package purchases, and digital product sales do not.

Checking that it is working

Once an audience or form is saved, the summary panel is your status board. Last synced: shows the date a real booking last pushed a contact through, and Last error: carries the provider's own wording for the most recent failure — a revoked key, a deleted audience, or a reply that took more than five seconds to arrive.

Test Connection is narrower than it looks: it asks the provider whether your key still works, and that is all — it pushes no contact and does not move Last synced:. The honest end-to-end check is to book a session on your own booking page with an address you can watch, then look for it in your list tool.

A sync failure never affects the booking. If your list tool is down or the key has been revoked, the session is still booked and your client still gets their confirmation — the failure is recorded as Last error: here and nowhere else. Glance at it any time you change something on the Mailchimp or Kit side.

Turning the sync off

Disconnect asks once, warning that this will remove the Mailchimp integration. New bookings will no longer sync contacts. Confirm and the key, the audience choice, and the tags go together — reconnecting later means pasting the key in again and rebuilding from the audience down.

Contacts already in your list are untouched, by this and by everything else Calso does — they are yours to manage in Mailchimp or Kit, as is anyone who unsubscribes from your Calso emails, since the two opt-out lists are entirely separate.

The rest of the Marketing & Analytics group measures bookings rather than collecting contacts: Track bookings with Google Analytics, Meta Pixel, or Tag Manager picks up from the same page.