HTML Structure

Required format

Default sends should use imageUrl, imageOrientation, messageText, and messageFontFamily.
frontHtml/backHtml are advanced overrides for template output or custom HTML.
Recommended size: 6.25in x 4.25in for full-bleed Lob output, with important content kept inside the 6in x 4in trim.
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: message content for the postcard back
Do not draw the recipient address, postage, postal barcode, or stamp box into either HTML field. Provide recipient data in to; tinypostcard and the print provider handle mailing/addressing separately.
Image fronts are best sent with imageUrl. Do not simulate requested generated artwork with HTML/CSS shapes.
For public agent/API payloads, tinypostcard places backHtml in the safe left message zone, about 2.3165in x 3.75in, and reserves Lob’s lower-right 3.2835in x 2.375in no-ink area for address, postage, barcode, and return-address handling.
For handwritten-style notes, set CSS font-family to one of the bundled fonts: "tpc-letters-home", "tpc-ugly-dave", "tpc-ugly-dave-alternates", "tpc-marina-script", or "Dancing Script".

Safe baseline template


<!doctype html>
<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <style>
      @page {
        size: 6.25in 4.25in;
        margin: 0;
      }
      html,
      body {
        margin: 0;
        padding: 0;
      }
      .card {
        width: 6.25in;
        height: 4.25in;
        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

Default sends should use imageUrl, imageOrientation, messageText, and messageFontFamily.

frontHtml/backHtml are advanced overrides for template output or custom HTML.

Recommended size: 6.25in x 4.25in for full-bleed Lob output, with important content kept inside the 6in x 4in trim.

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: message content for the postcard back

Do not draw the recipient address, postage, postal barcode, or stamp box into either HTML field. Provide recipient data in to; tinypostcard and the print provider handle mailing/addressing separately.

Image fronts are best sent with imageUrl. Do not simulate requested generated artwork with HTML/CSS shapes.

For public agent/API payloads, tinypostcard places backHtml in the safe left message zone, about 2.3165in x 3.75in, and reserves Lob’s lower-right 3.2835in x 2.375in no-ink area for address, postage, barcode, and return-address handling.

For handwritten-style notes, set CSS font-family to one of the bundled fonts: "tpc-letters-home", "tpc-ugly-dave", "tpc-ugly-dave-alternates", "tpc-marina-script", or "Dancing Script".

Safe baseline template


<!doctype html>
<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <style>
      @page {
        size: 6.25in 4.25in;
        margin: 0;
      }
      html,
      body {
        margin: 0;
        padding: 0;
      }
      .card {
        width: 6.25in;
        height: 4.25in;
        overflow: hidden;
      }
    </style>
  </head>
  <body>
    <div class="card">Hello postcard</div>
  </body>
</html>