Mailchimp’s Marketing API v3.0 has been stable since 2018, ships four official SDKs, and covers the full campaign and audience lifecycle. What it does not cover, as of August 2026, is Model Context Protocol. The Transactional side (Mandrill) has an official MCP server. The Marketing side does not. That gap has been filled by a growing set of community wrappers, some free on GitHub and some commercial with managed authentication. This tab inventories the API surface and the MCP landscape a buyer needs to evaluate before committing.

At a glance

MCP integration in 2026

Model Context Protocol is the emerging standard for connecting LLM agents to external tools. If you want an AI agent (Claude, ChatGPT, Cursor, custom OpenAI Agents SDK deployment) to read from or write to Mailchimp, MCP is now the connection layer of choice. Here is where Mailchimp stands.

Available MCP servers for Mailchimp

Seven options as of August 2026, ordered by maturity and coverage. Only the first is official Mailchimp. The rest are community or commercial third parties. Tap any card to open its documentation.

Marketing API v3.0 essentials

The Marketing API follows REST conventions with a few Mailchimp-specific quirks worth internalizing before writing your first request.

The API generally follows REST: resources are nouns (/lists, /campaigns, /reports), actions map to HTTP methods, and anything that does not map cleanly ends up under an /actions/ subresource (for example POST /campaigns/{campaign_id}/actions/send). Subresources can nest several levels deep: /lists/{list_id}/members/{subscriber_hash}/notes/{id} is a valid path.

Authentication methods

Two mechanisms, both operating on the same permission model.

HTTP Basic Auth (API key)

Simplest. Use any string as the username and your API key as the password. The Authorization header is base64-encoded automatically by every HTTP client. The API key has full account access and no scope restriction. Rotate keys through the Mailchimp UI (Account → Extras → API keys). Alternate form: Authorization: Bearer YOUR_API_KEY is also accepted.

OAuth 2.0

Required if you are building a third-party app that acts on behalf of Mailchimp users. Standard three-leg OAuth 2.0 flow: authorization code exchange for a bearer token. The resulting token inherits the authorizing user’s role and permissions. Also gives you the data center prefix through the OAuth metadata endpoint, which you must resolve before constructing any request URL.

Rate limits

Mailchimp’s rate-limiting model is simpler than most competitors: no daily quota, no per-endpoint budget, one hard constraint on concurrency.

The 10-connection ceiling is the number one thing that surprises developers coming from SendGrid or Postmark, both of which have more generous concurrent limits. Working around it: batch async operations through POST /3.0/batches, cache aggressively on your side, and coordinate multiple integrations on the same account so they do not compete for the same 10 slots.

Official SDKs

Four official client libraries for the Marketing API. All auto-generated from a single OpenAPI-derived codegen tool (mailchimp-client-lib-codegen).

Notable community SDKs

Mailchimp does not ship official SDKs for .NET, Java, Go, Rust, Kotlin, or Swift. Community wrappers fill the gap for .NET (MailChimp.Net.V3 by Brandon Seydel, MIT license, actively maintained, requires TLS 1.2) and to a lesser extent for Kotlin and Swift. For Go, Rust, or Java projects, most teams call the API directly with the standard HTTP client of their language.

Endpoints reference

The 15 endpoint groups you will actually use. Full reference at mailchimp.com/developer/marketing/api covers over 250 individual operations across all subresources.

Code examples

Two representative snippets covering the most common first-day tasks: ping the API to verify auth, then add a subscriber to a list.

Python: ping + add subscriber

import mailchimp_marketing as MailchimpMarketing
from mailchimp_marketing.api_client import ApiClientError
import hashlib

client = MailchimpMarketing.Client()
client.set_config({
    "api_key": "YOUR_API_KEY-us19",
    "server": "us19"
})

try:
    response = client.ping.get()
    print(response)
except ApiClientError as e:
    print(f"error: {e.text}")

# Add a subscriber (email lowercase, then MD5)
email = "user@example.com".lower()
subscriber_hash = hashlib.md5(email.encode()).hexdigest()

client.lists.set_list_member(
    list_id="abc123",
    subscriber_hash=subscriber_hash,
    body={
        "email_address": email,
        "status_if_new": "subscribed",
        "merge_fields": {"FNAME": "Alaa", "LNAME": "Touil"}
    }
)

Node.js: create and send a campaign

const mailchimp = require('@mailchimp/mailchimp_marketing');

mailchimp.setConfig({
    apiKey: 'YOUR_API_KEY-us19',
    server: 'us19',
});

async function sendCampaign(listId) {
    // 1. Create the campaign
    const campaign = await mailchimp.campaigns.create({
        type: 'regular',
        recipients: { list_id: listId },
        settings: {
            subject_line: 'Test from the API',
            from_name: 'SMTPedia',
            reply_to: 'hello@smtpedia.com'
        }
    });

    // 2. Set the HTML content
    await mailchimp.campaigns.setContent(campaign.id, {
        html: '
Hello
This is a test.
'
    });

    // 3. Send it
    await mailchimp.campaigns.send(campaign.id);
    console.log(`Sent campaign ${campaign.id}`);
}

sendCampaign('abc123').catch(console.error);

Common gotchas

Deprecations and changelog

Mailchimp maintains a public release notes feed at mailchimp.com/developer/release-notes. Key deprecations to know:

• API 2.0 and Export API 1.0 retired on June 1, 2023. Any legacy integration on those APIs stopped working that day. Migrate to v3.0.
• Marketing API v3.0 is current. No successor announced. No known deprecation timeline.
• Marketing API 2.0 is documented as “deprecated and unsupported” but has not been shut off. Mailchimp will announce a shutoff date in advance when they schedule one. Do not build anything new on it.
• Message search rate limit enforced – added as a distinct throttle in a July 2025 release-notes update. If your code loops /search-members or /search-campaigns, add backoff.
• Marketing SDKs frozen since November 2, 2022. No official acknowledgment or roadmap; the autogen infrastructure (mailchimp-client-lib-codegen) still exists but has not published updates.

Frequently asked questions