AFI
Kit
Kit (formerly ConvertKit) is an email marketing platform designed for creators. Advanced Form Integration subscribes form submitters to your Kit sequences and forms from WordPress form submissions, so every newsletter signup or lead capture grows your audience automatically.
What you’ll need
- An active Kit account.
- A Kit V4 API Key (see below).
- The Advanced Form Integration plugin installed and activated.
Get your Kit API key
- Sign in to your Kit account.
- Go to Account Settings → Developer.
- Create and copy your V4 API Key.
- In WordPress, go to AFI → Settings → Kit.
- Click Add Account, paste the API key, and give the account a name.
- Click Save.
Kit authenticates API requests using the X-Kit-Api-Key header with your V4 API key.
Create the integration
- Go to AFI → Add New.
- Give the integration a name, for example
Newsletter signup to Kit. - Under Trigger, pick the form plugin and the specific form you want to listen on.
- Under Action → Platform, select Kit.
- In Task, choose Subscribe To Sequence.
- Pick the saved account in the Account dropdown.
- Optional: select a Sequence to subscribe the contact to. AFI loads your sequences from the API.
- Optional: select a Form to subscribe through. Either a sequence or a form should be selected.
- Map your form fields onto the Kit fields listed below.
- Optional: open Conditional Logic to limit which submissions are sent.
- Click Save Integration.
Tasks supported
Subscribe To Sequence
Creates or updates a subscriber in Kit via POST /v4/subscribers with the state set to active. After the subscriber is created, AFI performs two optional follow-up calls:
- If a Sequence is selected, the subscriber is added to the sequence via
POST /v4/sequences/{id}/subscribers. - If a Form is selected, the subscriber is added through the form via
POST /v4/forms/{id}/subscribers.
At least one of sequence or form should be selected so the subscriber is enrolled in an automation flow.
| Field | Field key | Required | Notes |
|---|---|---|---|
email |
Yes | Subscriber email address | |
| First Name | firstName |
No |
Pro features
The Pro integration extends the free version with auto-loaded custom fields, tags during subscription, and a dedicated Tag a Subscriber task. Pro uses the same Kit API key connection.
Custom fields (auto-loaded)
Pro fetches custom field definitions from GET /v4/custom_fields. Each field appears in the mapper with its label, keyed as cf_{key}. Custom field values are sent under the fields object in the subscriber payload. You can also enter custom fields manually using the pipe-separated format key=value|key2=value2.
Tags during subscription
Pro adds a Tag field on the Subscribe task. Enter tag IDs as a comma-separated string. Tags are applied when the subscriber is created or updated. Available tags with their IDs are listed inline for reference.
Tag a Subscriber
Pro adds a dedicated Tag a Subscriber task that applies a single tag to an existing subscriber by email via POST /v4/tags/{id}/subscribers. The tag is selected from a dropdown of your workspace tags loaded from the API.
Feature comparison
| Feature | Free | Pro |
|---|---|---|
| Create/update subscriber | ✅ | ✅ |
| Subscribe to sequence | ✅ | ✅ |
| Subscribe via form | ✅ | ✅ |
| Email + first name | ✅ | ✅ |
| Custom fields (auto-loaded from API) | No | ✅ |
| Tags during subscription | No | ✅ |
| Tag a Subscriber (standalone task) | No | ✅ |
Conditional logic example
Only subscribe contacts to your “Course Buyers” sequence when the form’s purchase_type field is “course”. Free subscribers go to a general newsletter sequence via a separate integration.
Troubleshooting
Nothing arrives in Kit
Open AFI → Log and find the most recent entry for this integration. AFI stores the request URL, JSON body, and raw response from Kit. If there is no log entry at all, the trigger never fired: submit a real test entry from the front end.
Subscriber created but not added to sequence
The subscriber is created first, then added to the sequence in a second API call. If the email address is empty or the sequence subscription call fails, check the log for the specific error. Kit requires a valid email address for both calls.
API key rejected
Kit V4 uses the X-Kit-Api-Key header. Verify the key in Account Settings → Developer. If you recently migrated from ConvertKit, make sure you are using the V4 key, not the legacy V3 API secret.
Neither sequence nor form selected
If both the Sequence and Form dropdowns are left unselected, the subscriber is created but not enrolled in any automation. Select at least one so the subscriber enters a flow.