Kit Developer Documentation

Subscribe an endpoint to one or more event types with the events array when you create or update it. Each event arrives inside a delivery’s events array, and its data shape is described below.

Kit is rolling event types out incrementally. The events marked Available below deliver today; the rest are planned and listed so you can see what’s coming. Planned events can’t be subscribed to yet: the API rejects them with a 422 and the create panel in Kit doesn’t offer them. They become subscribable the day they ship.

Subscriber events

Event	Status
`subscriber.created`	Available
`subscriber.activated`	Available
`subscriber.unsubscribed`	Available
`subscriber.bounced`	Available
`subscriber.complained`	Available
`subscriber.subscribed_to_form`	Available
`subscriber.added_to_sequence`	Available
`subscriber.sequence_completed`	Available
`subscriber.tag_added`	Available
`subscriber.tag_removed`	Available
`subscriber.custom_field_value_updated`	Available
`subscriber.product_purchased`	Planned
`subscriber.link_clicked`	Planned
`subscriber.email_opened`	Planned

Resource events

Event	Status
`tag.created`, `tag.deleted`	Available
`custom_field.created`, `custom_field.deleted`	Available
`sequence.created`, `sequence.deleted`, `sequence.published`, `sequence.disabled`	Available
`broadcast.created`, `broadcast.sent`, `broadcast.deleted`	Available
`post.published`	Available
`landing_page.created`, `landing_page.deleted`	Planned

Payloads

Subscriber events carry the subscriber object, plus the related resource where one exists. The subscriber object matches the shape returned by the V4 subscribers API:

{
  "subscriber": {
    "id": 987654,
    "first_name": "Ada",
    "email_address": "ada@example.com",
    "state": "active",
    "created_at": "2026-07-29T14:32:10Z",
    "fields": { "company": "Kit" }
  }
}

`subscriber.created`

Fires when a subscriber is added to the account. data carries the subscriber object above.

`subscriber.activated`

Fires when a subscriber transitions into the active state. data carries the subscriber object above.

`subscriber.unsubscribed`, `subscriber.bounced`, `subscriber.complained`

Fire when a subscriber unsubscribes, when their address hard-bounces, and when they report an email as spam. Each carries the subscriber object above, whose state reflects the new status.

`subscriber.subscribed_to_form`

Fires when a subscriber joins a form. Includes both the subscriber and the form.

{
  "subscriber": { "...": "..." },
  "form": {
    "id": 55,
    "name": "Newsletter signup",
    "created_at": "2026-05-01T08:15:00Z",
    "type": "embed",
    "format": "inline",
    "archived": false,
    "uid": "abc123"
  }
}

`subscriber.added_to_sequence` and `subscriber.sequence_completed`

Fire when a subscriber starts a sequence, and when they finish its last email. Both include the sequence.

{
  "subscriber": { "...": "..." },
  "sequence": {
    "id": 77,
    "name": "Welcome series",
    "hold": false,
    "repeat": false,
    "created_at": "2026-05-01T08:15:00Z",
    "updated_at": "2026-07-01T10:00:00Z",
    "email_template_id": 3,
    "active": true
  }
}

`subscriber.tag_added` and `subscriber.tag_removed`

Fire when a tag is added to or removed from a subscriber. Both include the tag. Deleting a tag does not fire subscriber.tag_removed for each subscriber that had it — you get a single tag.deleted event instead (see below).

{
  "subscriber": { "...": "..." },
  "tag": {
    "id": 42,
    "name": "customer",
    "created_at": "2026-05-01T08:15:00Z"
  }
}

`subscriber.custom_field_value_updated`

Fires when a custom field value changes on a subscriber — one event per field changed. Includes the field and its new value.

{
  "subscriber": { "...": "..." },
  "custom_field": {
    "id": 9,
    "name": "ck_field_9_company",
    "key": "company",
    "label": "Company",
    "value": "Kit"
  }
}

`sequence.created`, `sequence.deleted`, `sequence.published`, `sequence.disabled`

Fire on the sequence itself, not on a subscriber. data carries the sequence object shown above.

`tag.created` and `tag.deleted`

Fire when a tag is created or deleted on the account. These are resource events — data carries the tag itself, no subscriber.

{
  "tag": {
    "id": 42,
    "name": "customer",
    "created_at": "2026-05-01T08:15:00Z"
  }
}

Deleting a tag removes it from every subscriber at once, but Kit emits only the one tag.deleted event — there is no subscriber.tag_removed per subscriber. If you mirror tag membership, drop the tag from all subscribers when you receive tag.deleted.

`broadcast.created`, `broadcast.sent`, `broadcast.deleted`

Fire when a broadcast is created, when its send completes, and when it’s deleted. data carries a summary of the broadcast; fetch the full representation, including content, from the V4 broadcasts API.

{
  "broadcast": {
    "id": 5001,
    "publication_id": 12,
    "created_at": "2026-07-28T09:00:00Z",
    "subject": "This week's update",
    "preview_text": "What's new at Kit",
    "description": "Weekly newsletter",
    "public": true,
    "published_at": "2026-07-29T14:00:00Z",
    "send_at": "2026-07-29T14:00:00Z",
    "status": "completed"
  }
}

`post.published`

Fires when a post is published. data carries a summary of the post; fetch the full content from the V4 posts API.

{
  "post": {
    "id": 8801,
    "publication_id": 12,
    "title": "Hello, world",
    "slug": "hello-world",
    "published_at": "2026-07-29T14:00:00Z",
    "is_paid": false,
    "public_url": "https://example.kit.com/posts/hello-world"
  }
}

`custom_field.created` and `custom_field.deleted`

Fire when a custom field is created or deleted on the account. These are resource events — data carries the field itself, no subscriber.

{
  "custom_field": {
    "id": 9,
    "name": "ck_field_9_company",
    "key": "company",
    "label": "Company"
  }
}

Getting started

Guides

Webhooks

Endpoints

Event types

Subscriber events

Resource events

Payloads

`subscriber.created`

`subscriber.activated`

`subscriber.unsubscribed`, `subscriber.bounced`, `subscriber.complained`

`subscriber.subscribed_to_form`

`subscriber.added_to_sequence` and `subscriber.sequence_completed`

`subscriber.tag_added` and `subscriber.tag_removed`

`subscriber.custom_field_value_updated`

`sequence.created`, `sequence.deleted`, `sequence.published`, `sequence.disabled`

`tag.created` and `tag.deleted`

`broadcast.created`, `broadcast.sent`, `broadcast.deleted`

`post.published`

`custom_field.created` and `custom_field.deleted`

​Subscriber events

​Resource events

​Payloads

​subscriber.created

​subscriber.activated

​subscriber.unsubscribed, subscriber.bounced, subscriber.complained

​subscriber.subscribed_to_form

​subscriber.added_to_sequence and subscriber.sequence_completed

​subscriber.tag_added and subscriber.tag_removed

​subscriber.custom_field_value_updated

​sequence.created, sequence.deleted, sequence.published, sequence.disabled

​tag.created and tag.deleted

​broadcast.created, broadcast.sent, broadcast.deleted

​post.published

​custom_field.created and custom_field.deleted

Subscriber events

Resource events

Payloads

`subscriber.created`

`subscriber.activated`

`subscriber.unsubscribed`, `subscriber.bounced`, `subscriber.complained`

`subscriber.subscribed_to_form`

`subscriber.added_to_sequence` and `subscriber.sequence_completed`

`subscriber.tag_added` and `subscriber.tag_removed`

`subscriber.custom_field_value_updated`

`sequence.created`, `sequence.deleted`, `sequence.published`, `sequence.disabled`

`tag.created` and `tag.deleted`

`broadcast.created`, `broadcast.sent`, `broadcast.deleted`

`post.published`

`custom_field.created` and `custom_field.deleted`