Kit (ConvertKit) API + MCP (2026): v4 REST and Two First-Party MCP Servers

Kit’s API v4 is the modern REST API for programmatic access to subscribers, tags, forms, sequences, broadcasts, and Kit Commerce. Simple API key authentication, JSON payloads, published rate limits (600 requests per rolling 60 seconds on an OAuth token, 120 on an API key), well-documented webhook subscriptions. What Kit also ships in 2026: two first-party Model Context Protocol servers, documented next to the API itself. Kit MCP lets an AI client act on a creator account; Kit Developer Docs MCP serves these docs to a coding agent. The community wrappers that covered the gap before them still run, but they are no longer the only route.

At a glance

MCP integration in 2026

Model Context Protocol is the emerging standard for connecting LLM agents to external tools. Kit ships two first-party servers for it and documents both: Kit MCP, which acts on a creator account, and Kit Developer Docs MCP, which serves the documentation to a coding agent. The community wrappers listed below predate them and still work.

Community and third-party MCP servers for Kit

API v4 essentials

Authentication methods

API key (X-Kit-Api-Key header)

Simplest and most common for internal use. Generate an API key in your Kit account under Account › Settings › Advanced › API. Send it in the request header:

X-Kit-Api-Key: YOUR_API_KEY
Content-Type: application/json
Accept: application/json

API keys are account-scoped and inherit full account permissions. No granular scopes, a token can do anything the account allows. Rotate keys promptly if compromised.

OAuth 2.0 (for public apps)

Required for third-party apps published in the Kit integration marketplace. Standard three-leg authorization code flow. Register your app in the Kit Developer Portal. Access tokens have long lifetimes; no refresh required for most use cases.

Rate limits

The ceiling depends on how you authenticate, which is the part worth planning around: 600 requests per rolling 60 seconds for an OAuth app, 120 for a script holding an API key. A large migration (100K+ subscribers moving in a batch) reaches the API key ceiling long before it reaches the OAuth one. Use the batch endpoints for bulk operations, and back off exponentially on a 429.

Official SDKs

Kit’s official SDK footprint is thin (2 official). For Python, Ruby, .NET, and other languages, community wrappers exist but quality varies. Direct API calls with your language’s HTTP client are often safer than an unmaintained community SDK.

Endpoints reference

Code examples

Node.js: add subscriber and tag

const axios = require('axios');

const API_KEY = 'YOUR_API_KEY';
const BASE_URL = 'https://api.kit.com/v4';

async function subscribeWithTag(email, tagId) {
  // 1. Create subscriber
  const created = await axios.post(
    `${BASE_URL}/subscribers`,
    {
      email_address: email,
      first_name: 'Alaa',
      state: 'active'
    },
    { headers: { 'X-Kit-Api-Key': API_KEY } }
  );

  // 2. Add tag
  await axios.post(
    `${BASE_URL}/tags/${tagId}/subscribers`,
    { email_address: email },
    { headers: { 'X-Kit-Api-Key': API_KEY } }
  );

  console.log(`Subscribed and tagged: ${created.data.subscriber.id}`);
}

subscribeWithTag('user@example.com', 'YOUR_TAG_ID');

Common gotchas

Deprecations and changelog

• API v4 is current. Modern REST API with cleaner authentication and better documentation.
• API v3 deprecated. Legacy integrations should migrate to v4 promptly.
• Two official MCP servers documented in 2026: Kit MCP at https://app.kit.com/mcp on Creator and Creator Pro, and the public Kit Developer Docs MCP. Community wrappers remain as alternatives.
• ConvertKit renamed to Kit in 2024. API and product names transitioning; some docs still reference “ConvertKit”.
• Kit Commerce API endpoints matured in 2024-2025 for programmatic creator commerce integration.

Frequently asked questions