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

Provided free and as is, without warranty of any kind — including merchantability, fitness for a particular purpose, and the accuracy or completeness of any result. See the licence. You are responsible for checking what this produces before relying on it.

ConvertKit (Kit)

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

Publishes

The keys a later task may reference as {{taskName.key}}. Referencing anything not listed here resolves to nothing at run time.

error
result
status

Input Properties

Every property this tool accepts, from its own tool.iml.

Property	Type	Required	Default	Description
`apiKey`	string	yes	—	DEPRECATED — bind an API Key credential to the task with `credentialName` instead. A key pasted here is stored in the workflow definition in clear and appears in every export of it. Still honoured for workflows built before the change.
`operation`	string	yes	—	One of: list-tags, tag-contact, add-to-sequence, create-broadcast
`tagId`	string	no	—	Numeric tag id. Required for tag-contact. Get ids from list-tags.
`sequenceId`	string	no	—	Numeric sequence id. Required for add-to-sequence.
`emailAddress`	string	no	—	Contact email address. Required for tag-contact and add-to-sequence. The contact must already exist in Kit.
`subject`	string	no	—	Broadcast email subject line. Required for create-broadcast.
`content`	string	no	—	Broadcast email HTML body content. Required for create-broadcast.
`sendAt`	string	no	—	Optional ISO8601 scheduled send time for create-broadcast (e.g. 2026-07-01T09:00:00Z). Leave empty to save the broadcast as a draft.