How do I add people to a date workflow from another system, with their own date?

Sound familiar?

People sign up or buy through another system, such as your booking tool, a form builder or Zapier, and you want them to start a follow-up sequence in Co-Kinetic. The catch is that the sequence depends on a date that only the other system knows: when they bought, when their voucher expires, or when their appointment is 🔗.

What's happening

Every workflow has its own Workflow Webhook URL. Another system can send a person to that address and they're added to the workflow. For a workflow built on Each person's own date, the other system can also send that person's date. Their emails are then timed from it.

Why it works this way

Your contacts don't all start in Co-Kinetic. A webhook is the common language most systems speak, so it's the simplest way to connect them. Sending the date at the same moment means the other system's knowledge (when they bought, when it expires) drives your emails, with nothing typed in by hand ⚙️.

What to do now

1. Create a workflow with Each person's own date (see "Which kind of email workflow should I use?").
2. Under What starts each person's clock?, choose A date supplied by the system that enrols them (webhook).
3. Set a deadline if you need one, for example Yes, their date plus 30 days for a 30-day offer.
4. Create the workflow, add your emails and set their timings.
5. On the workflow's page, copy its Workflow Webhook URL.
6. In the other system, send each new person to that URL with their details and their date in a field called key_date, written as DD/MM/YYYY (for example 25/10/2026).
7. Switch the workflow's Active toggle on, then send one test person and check them in Who gets what, and when.

If you want more detail

• No date sent means the person is held. If the workflow needs a date and none arrives, the person is added but nothing is scheduled, and the workflow card shows a flag. Nothing is guessed. Add their date and their emails start.
• The date is read as a calendar day in your time zone. 25/10/2026 means 25 October where you are.
• If you don't need a date from the other system, choose The moment they join this workflow (via a form, tag or rule) instead. Their clock starts when they arrive.
• Shared-date workflows can use the webhook too. People sent to a shared-date workflow simply join, and their emails are timed from the shared date. No key_date is needed.
• Unsubscribed contacts are never emailed, however they were added.

The question behind the question

"Do I need a developer for this?" Usually not. Tools like Zapier and Make can send a webhook without code: you paste the URL and match the fields. If your system can't do it, ask us in the chat and we'll point you at the right route 🙂.

The next question is usually...

• How do I bring contacts into Co-Kinetic from other systems?
• How do I check who gets which email, and when?
• How does email timing work when a workflow runs around a date?

Still stuck? This usually means...

• People arrive but show as held. The date isn't reaching us. Check the field is called key_date and the date is written DD/MM/YYYY.
• People don't arrive at all. Check the URL was copied in full from the workflow's own page, and that the other system is sending an email address.
• You can't see the option for a date supplied by the system. It's under What starts each person's clock?, which appears when you choose Each person's own date.
• Anything else. Tell us in the chat with the workflow name and the system you're connecting.