The What's Next section at the bottom of this page will take you to the correct documentation. But first, the subsequent article includes a high-level overview of the Inkit Postcards API and the Inkit Letters API.

Postcards

The Inkit Postcards API endpoint allows you to easily print and mail postcards. The API provides endpoints for creating postcards, retrieving individual postcards, canceling postcards, and retrieving a list of postcards.

Letters

The Inkit Letters API endpoint allows you to easily print and mail letters. The API provides endpoints for creating letters, retrieving individual letters, canceling letters, and retrieving a list of letters.