HTML Structure

Required format

frontHtml and backHtml must both be valid HTML strings.
Recommended size: exactly 6in x 4in postcard canvas.
Max size per HTML field: 2,000,000 characters.

Rendering behavior

Send endpoint accepts user-facing frontHtml and backHtml.
Internally, print provider field mapping is handled by tinypostcard.
You should always pass payload fields using normal names:
- frontHtml: what you want on postcard front
- backHtml: what you want on postcard back

Safe baseline template


<!doctype html>
<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <style>
      @page {
        size: 6in 4in;
        margin: 0;
      }
      html,
      body {
        margin: 0;
        padding: 0;
      }
      .card {
        width: 6in;
        height: 4in;
        overflow: hidden;
      }
    </style>
  </head>
  <body>
    <div class="card">Hello postcard</div>
  </body>
</html>

Reusing existing public templates

Use template endpoints to source production-safe HTML:

GET /api/v1/templates?scope=shared
GET /api/v1/templates/{templateId}/html

This is the fastest way for agents to avoid HTML formatting issues.

Required format

frontHtml and backHtml must both be valid HTML strings.
Recommended size: exactly 6in x 4in postcard canvas.
Max size per HTML field: 2,000,000 characters.

Rendering behavior

Send endpoint accepts user-facing frontHtml and backHtml.
Internally, print provider field mapping is handled by tinypostcard.
You should always pass payload fields using normal names:
- frontHtml: what you want on postcard front
- backHtml: what you want on postcard back

Safe baseline template


<!doctype html>
<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <style>
      @page {
        size: 6in 4in;
        margin: 0;
      }
      html,
      body {
        margin: 0;
        padding: 0;
      }
      .card {
        width: 6in;
        height: 4in;
        overflow: hidden;
      }
    </style>
  </head>
  <body>
    <div class="card">Hello postcard</div>
  </body>
</html>

Reusing existing public templates

Use template endpoints to source production-safe HTML:

GET /api/v1/templates?scope=shared
GET /api/v1/templates/{templateId}/html

This is the fastest way for agents to avoid HTML formatting issues.