Tag subscribers and trigger broadcasts/sequences for creators via the ConvertKit (Kit) v4 API.

ConvertKit (Kit)

Name: ConvertKit (Kit)
Author: Blue Isle

Tag subscribers and trigger broadcasts/sequences for creators via the ConvertKit (Kit) v4 API.

Base URL: https://api.kit.com
Auth: X-Kit-Api-Key: <API_KEY> header (single API key — no OAuth/JWT required)

Operations

operation	Kit endpoint	Purpose
`list-tags`	`GET /v4/tags`	List your tags (and their numeric ids)
`tag-contact`	`POST /v4/tags/{tagId}/subscribers`	Apply a tag to an existing contact by email
`add-to-sequence`	`POST /v4/sequences/{sequenceId}/subscribers`	Add an existing contact to a sequence by email
`create-broadcast`	`POST /v4/broadcasts`	Draft or schedule a broadcast email

The contact being tagged or added to a sequence must already exist in Kit.

API key setup

Sign in to your Kit (ConvertKit) account.
Go to Settings > Advanced > API.
Copy your API Key (the v4 key).
Pass it as the apiKey input. The tool sends it as the X-Kit-Api-Key header.

Inputs

input	required for	description
`apiKey`	all	Kit v4 API Key
`operation`	all	One of the operations above
`tagId`	`tag-contact`	Numeric tag id (from `list-tags`)
`sequenceId`	`add-to-sequence`	Numeric sequence id
`emailAddress`	`tag-contact`, `add-to-sequence`	Contact email
`subject`	`create-broadcast`	Email subject line
`content`	`create-broadcast`	Email HTML body
`sendAt`	optional (`create-broadcast`)	ISO8601 send time to schedule; empty = save draft

Outputs

result — the Kit response body as a JSON string
status — the HTTP status code

Examples

List tags

operation: list-tags
apiKey:    <your key>

Tag a contact by email

operation:    tag-contact
apiKey:       <your key>
tagId:        207
emailAddress: [email protected]

Add a contact to a sequence

operation:    add-to-sequence
apiKey:       <your key>
sequenceId:   91
emailAddress: [email protected]

Draft a broadcast (omit sendAt)

operation: create-broadcast
apiKey:    <your key>
subject:   This week in the studio
content:   <h1>Hello!</h1><p>Here's what's new...</p>

Schedule a broadcast

operation: create-broadcast
apiKey:    <your key>
subject:   This week in the studio
content:   <h1>Hello!</h1><p>Here's what's new...</p>
sendAt:    2026-07-01T09:00:00Z