Key concepts

Modifications

modifications is the object you send with a render request to override a template's parameters. It's a flat map from variableName to a replacement value — every key must match a variable name that exists on the template (see list_template_parameters to discover them).

modifications
{
  "headline": "50% off today",
  "backgroundImage": "https://example.com/sale-bg.jpg",
  "accentColor": "#ff5a1f"
}
ParamTypeNotes
formatstringEvery value is passed as a string, regardless of the underlying layer type — image URLs and hex colors included.
unmatched keysA key that doesn't match any variableName on the template is ignored, not rejected.