ConvertKit (Kit) API V3
★ 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.
Use for: I need to add a subscriber to a specific form, I want to tag a subscriber to trigger an automation, List all subscribers with a specific tag, Get the open rate statistics for a recent broadcast
Not supported: Does not handle payment processing, landing page hosting, or CRM deal tracking — use for email subscriber management, sequence automation, and broadcast delivery only.
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.
Install Jentic One Beta
Connect the ConvertKit (Kit) API V3 to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the ConvertKit (Kit) API V3, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.
Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.
1
Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh
jentic register # connects your agent to your Jentic One instanceJentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.
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
Record purchases with product details and revenue for purchase-based automation triggers
Register webhook automations triggered by subscriber events like form sign-ups and tag additions
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
Register an automation webhook
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
Register an automation webhook
Why 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.
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}.
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