Developer docs
Build against the real Constant Contact public interfaces
These docs cover the supported public REST API and public MCP surface: API keys, sending, domains, send status, webhooks, MCP discovery, tools, resources, prompts, retries, rate limits, and error handling.
Start here: make server-side HTTP requests with
Authorization: Bearer <API_KEY>. Do not ship API keys in browser code.
Core docs
Documentation Overview
Start from the supported REST and MCP documentation overview.
Quickstart
Send a transactional email with the required bearer token and idempotency key.
API Reference
OpenAPI-backed endpoint and schema documentation rendered with Scalar.
Interactive Explorer
Try supported API endpoints in a browser-hosted OpenAPI explorer.
OpenAPI Spec
Download the OpenAPI YAML used by the reference and explorer.
Deep guides
The left rail exposes the supported guide set directly: auth, domain verification, idempotency, send status, webhooks, retries, rate limits, errors, glossary, examples, and MCP. Use the overview cards above for the fastest entry points, then move through the rail when you need a focused implementation guide.
Also useful
Constant Contact V3 API documentation
Use the official V3 docs for the established Constant Contact marketing APIs. This site documents the newer transactional public REST surface.
Official V3 docs
External link