Mailchimp

Mailchimp Marketing API v3.0 provides comprehensive email marketing automation with RESTful endpoints for audiences, campaigns, automations, and analytics.

Authentication uses API keys with data center-specific URLs (e.g., us6.api.mailchimp.com) or OAuth 2.0 for third-party integrations. The API covers 200+ endpoints including audience management, campaign creation, automation workflows, reporting, e-commerce integration, and webhooks for real-time updates.

Official client libraries available for major languages. Features include pagination (max 1000 items), partial responses via field filtering, batch operations, and 120-second timeout on calls. MD5 email hashing protects contact privacy. Transactional API (Mandrill) available separately.

Free tier available with feature limitations on paid plans. OpenAPI specification provided. Ideal for marketing automation, CRM integration, custom dashboards, and multi-channel customer engagement with extensive integration marketplace.