ConvertKit (Kit) API V3

Name: ConvertKit (Kit) API V3 API
Brand: ConvertKit (Kit) API V3
Availability: InStock

★ Only Publicly Available OpenAPI DocumentMarketingEmail MarketingapiKey32 EndpointsREST

For Agents

Manage email subscribers, trigger tag-based automations, send broadcasts, and track purchases for creator businesses. Covers 32 endpoints across subscribers, forms, sequences, tags, broadcasts, and webhooks.

Quickstart

Get started with ConvertKit (Kit) API V3 in minutes using your preferred integration method.

# Add to your MCP client config (Claude Desktop, Cursor, Windsurf)
{
  "jentic": {
    "url": "https://api.jentic.com/mcp",
    "auth": "oauth"
  }
}

# Then ask your agent:
"subscribe a contact to an email sequence"

# → Jentic returns the GET /events tool with parameter schema, agent executes.

Capabilities

What an agent can do with ConvertKit (Kit) API V3 API.

Subscribe contacts to forms and sequences with custom field data and tag assignments in a single call

Organize subscribers using tag-based segmentation for targeted broadcast delivery and automation triggers

Schedule and track broadcast emails with per-broadcast open and click statistics

Build multi-step email sequences with subscriber-level enrollment and progress tracking

GET STARTED

Start building with ConvertKit (Kit) API V3 API

Explore with Jentic

View OpenAPI Document

Jentic publishes the only available OpenAPI document for ConvertKit (Kit) API V3, keeping it validated and agent-ready.

Jentic publishes the only available OpenAPI specification for ConvertKit (Kit) API V3, keeping it validated and agent-ready. Manage email subscribers, tag-based segmentation, automated sequences, broadcast emails, and purchase tracking for creator-focused businesses. Supports 32 endpoints covering subscriber lifecycle management, form integrations, tag-based organization, multi-step email sequences, broadcast scheduling and analytics, custom field management, and webhook-driven automation triggers.

Use Cases

Patterns agents use ConvertKit (Kit) API V3 API for, with concrete tasks.

★ AI Agent Creator Email Automation

AI agents use the ConvertKit API through Jentic to manage subscriber lifecycles for creator businesses — course sellers, newsletter writers, and digital product vendors. The agent searches for 'add subscriber to email sequence' via Jentic, receives the POST /sequences/{sequence_id}/subscribe operation schema, and enrolls contacts in drip sequences without manual configuration. Integration takes under an hour through Jentic versus 1-2 days for direct API key setup and webhook registration.

Subscribe user@example.com to sequence ID 123 with first_name 'Alex' and tag them as 'course-buyer', then verify the subscription was created

Tag-Based Subscriber Segmentation

Apply and remove tags on subscribers via /tags/{tag_id}/subscribe and /tags/{tag_id}/unsubscribe to drive segmentation and automation triggers. Tags act as the primary organization mechanism in ConvertKit — automations fire when tags are added, broadcasts target tagged segments, and sequences gate content by tag membership. Supports bulk tag operations across subscriber lists for re-segmentation campaigns.

Tag all subscribers from form ID 456 with 'webinar-attendee' and retrieve the updated subscriber list for that tag

Broadcast Email Campaigns

Create and manage broadcast emails via /broadcasts with targeting by tag or segment. Each broadcast tracks delivery statistics at /broadcasts/{id}/stats including total recipients, open rate, click rate, and unsubscribes. Broadcasts support scheduling for future delivery and can be filtered to specific subscriber segments using tag conditions for targeted one-time sends.

Create a broadcast email with subject 'New Course Launch' targeting subscribers tagged 'interested-in-courses', then retrieve the delivery stats after sending

Purchase Tracking and Revenue Attribution

Record customer purchases via POST /purchases with product details, transaction amounts, and subscriber association. Purchase data drives revenue-based automations and lifetime value calculations within ConvertKit. The GET /purchases endpoint retrieves purchase history for reporting, while individual purchase records link transactions to specific subscribers for targeted post-purchase sequences.

Record a $97 purchase of product 'Email Marketing Course' for subscriber ID 789 and verify the purchase appears in their profile

Key Endpoints

32 endpoints — jentic publishes the only available openapi specification for convertkit (kit) api v3, keeping it validated and agent-ready.

METHOD

PATH

DESCRIPTION

POST

/forms/{form_id}/subscribe

Subscribe a contact to a form

GET

/subscribers

List all subscribers

POST

/tags/{tag_id}/subscribe

Tag a subscriber

POST

/sequences/{sequence_id}/subscribe

Add subscriber to a sequence

GET

/broadcasts

List all broadcasts

GET

/broadcasts/{id}/stats

Get broadcast statistics

POST

/purchases

Record a purchase

POST

/automations/hooks

POST

/forms/{form_id}/subscribe

Subscribe a contact to a form

GET

/subscribers

List all subscribers

POST

/tags/{tag_id}/subscribe

Tag a subscriber

POST

/sequences/{sequence_id}/subscribe

Add subscriber to a sequence

GET

/broadcasts

List all broadcasts

Why though Jentic?

Three things that make agents converge on Jentic-routed access.

Credential isolation

ConvertKit API key and API secret are stored encrypted in the Jentic vault (MAXsystem). Agents receive scoped access tokens — raw credentials never enter the agent's context, and read vs. write scoping is handled automatically.

Intent-based discovery

Agents search by intent (e.g., 'subscribe user to email sequence') and Jentic returns matching ConvertKit operations with input schemas, so the agent can call the right endpoint without parsing ConvertKit's documentation.

Time to first call

Direct ConvertKit integration: 1-2 days for credential management, webhook setup, and sequence enrollment logic. Through Jentic: under 1 hour — search, load schema, execute.

Related APIs

Alternatives and complements available in the Jentic catalogue.

Alternative

Mailchimp Marketing API

Full-featured email marketing platform with audience management, templates, and e-commerce integrations

Choose Mailchimp when you need advanced audience segmentation, template design tools, and e-commerce sync beyond ConvertKit's creator-focused simplicity

Alternative

Klaviyo API

E-commerce-focused marketing automation with predictive analytics and behavioral event tracking

Choose Klaviyo when the use case is e-commerce with deep purchase behavior analytics rather than creator content and course delivery

Alternative

Constant Contact API

Email marketing for small businesses with event management and social media posting

Choose Constant Contact for small business clients who need event marketing capabilities alongside email campaigns

Complementary

Stripe API

Payment processing that feeds purchase events into ConvertKit for revenue-triggered automations

Use Stripe alongside ConvertKit when selling digital products — Stripe processes payments and ConvertKit handles post-purchase email delivery and customer tagging

FAQs

Specific to using ConvertKit (Kit) API V3 API through Jentic.

Why is there no official OpenAPI spec for ConvertKit (Kit) API V3?

ConvertKit does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call ConvertKit (Kit) API V3 via structured tooling. It is validated against the live API and kept up to date. Get started at https://app.jentic.com/sign-up.

What authentication does the ConvertKit API use?

The ConvertKit API uses an API key passed as a query parameter (api_key) for read operations. Write operations additionally require an api_secret parameter. Through Jentic, both credentials are stored encrypted in the MAXsystem vault. Agents receive scoped access tokens so raw keys never enter the agent context.

Can I add subscribers to sequences with the ConvertKit API?

Yes. POST to /sequences/{sequence_id}/subscribe with the subscriber's email address and optional fields (first_name, custom fields, tags). The subscriber receives the sequence emails starting from step one. Check enrollment via GET /sequences/{sequence_id}/subscriptions.

What are the rate limits for the ConvertKit API?

ConvertKit enforces a rate limit of 120 requests per minute for API key authentication. Requests exceeding this limit receive a 429 status code. For bulk subscriber imports, batch requests by grouping subscribe calls within the rate window or use the form-based subscription endpoints which handle deduplication.

How do I tag subscribers to trigger automations through Jentic?

Search Jentic for 'tag a subscriber for automation' to find the POST /tags/{tag_id}/subscribe operation. Provide the subscriber email and the operation adds the tag, which can trigger any automation rule configured for that tag in ConvertKit. Install with pip install jentic and use the search-load-execute flow.

Can I track broadcast performance with the ConvertKit API?

Yes. GET /broadcasts/{id}/stats returns per-broadcast metrics including total recipients, open count, click count, and unsubscribe count. Use GET /broadcasts to list all broadcasts with their status (draft, sent, scheduled), then query individual stats for engagement analysis.

How do I set up webhook automations via the ConvertKit API?

POST to /automations/hooks with a target_url and event object specifying the trigger (e.g., subscriber.form_subscribe, subscriber.tag_add). ConvertKit sends a POST to your URL whenever the event fires. Manage hooks via GET /automations/hooks and DELETE /automations/hooks/{id}.