Every T-Shirt Color Variant Mockup from One PSD by API

After upload, GET /api/v1/psd-mockups/{uuid} lists the template's smart objects. The t-shirt template used here returns two (position, size and thumbnails left out):

{
  "data": {
    "smart_objects": [
      { "uuid": "ea565e8a-2b2b-46a1-b181-ff19d0e18eac", "name": "color", "blend_mode": "multiply" },
      { "uuid": "39865245-8d99-42e9-b1fc-3713fa4dbc94", "name": "print_area", "blend_mode": "normal" }
    ]
  }
}

• color covers the whole shirt and is set to Multiply in the file. Multiply is what keeps the folds and shadows of the fabric visible under the new color.
• print_area is where the design goes.

A template with only a print smart object renders any design you send, on the shirt color it was built with. For color variants, the template designer adds the color smart object in Photoshop before upload. The PSD template guide covers how to build and test the rest of the file.

One render takes the design for print_area and a color for color. This is the request, with the asset URL as a placeholder:

curl -X POST https://api.sudomock.com/api/v1/renders \
  -H "x-api-key: $SUDOMOCK_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "mockup_uuid": "e532c503-fe20-4653-a301-af9f7a934609",
    "smart_objects": [
      { "uuid": "39865245-8d99-42e9-b1fc-3713fa4dbc94",
        "asset": { "url": "https://example.com/designs/sunrise.svg", "fit": "fit" } },
      { "uuid": "ea565e8a-2b2b-46a1-b181-ff19d0e18eac",
        "color": { "hex": "#1E293B", "blending_mode": "multiply" } }
    ],
    "export_options": { "image_format": "webp", "image_size": 1024 },
    "export_label": "tee-navy"
  }'

Use the UUIDs from your own upload response. The image URL comes back in data.print_files[0].export_path. For the whole color list, loop over it and change the hex, the label and, for light blanks, the design:

const colors = {
  white: ['#FFFFF1', darkInkDesignUrl],
  black: ['#121403', designUrl],
  navy: ['#1E293B', designUrl],
  red: ['#BA0000', designUrl],
};

for (const [name, [hex, url]] of Object.entries(colors)) {
  const res = await fetch('https://api.sudomock.com/api/v1/renders', {
    method: 'POST',
    headers: { 'x-api-key': process.env.SUDOMOCK_API_KEY, 'Content-Type': 'application/json' },
    body: JSON.stringify({
      mockup_uuid: MOCKUP_UUID,
      smart_objects: [
        { uuid: PRINT_AREA_UUID, asset: { url, fit: 'fit' } },
        { uuid: COLOR_UUID, color: { hex, blending_mode: 'multiply' } },
      ],
      export_options: { image_format: 'webp', image_size: 1024 },
      export_label: `tee-${name}`,
    }),
  });
  const { data } = await res.json();
  console.log(name, data.print_files[0].export_path);
}

Here is one design on six colors: white #FFFFF1, heather gray #989987, black #121403, navy #1E293B, forest green #033F05 and red #BA0000.

White #FFFFF1	Heather gray #989987	Black #121403

Navy #1E293B	Forest green #033F05	Red #BA0000

Same template, same request. Only color.hex changed, and the white shirt got the dark-ink artwork.

Light ink on a light blank. Cream ink reads on dark shirts and fades on white. Keep a dark-ink version of the design for light blanks and send it in the requests for those colors, as the white shirt above does.

Use your blank's colors. Take hex values from your blank supplier's color chart. The template's light and the fabric's shading carry through every color, so folds and shadows look like a real shirt.

If your catalog already names its colors, save those names on the mockup once and render by name. PATCH /api/v1/psd-mockups/{uuid} takes a colors list of { "label", "hex" } pairs. The list replaces the saved palette, so send every color you want to keep.

{
  "colors": [
    { "label": "heather gray", "hex": "#989987" },
    { "label": "forest", "hex": "#033F05" }
  ]
}

Each render then sends "color": { "label": "forest", "blending_mode": "multiply" } in place of the hex. Labels match exactly. The fields follow the API reference for updating a PSD mockup.

Every color of every design is one render, so 40 designs in 6 colors is 240 requests against one template. Renders run in parallel up to your plan's concurrency, and past that the API answers 429 with a Retry-After header. For a large batch, send "is_async": true and collect the finished images by polling GET /api/v1/jobs/{job_id} or from a webhook: a queued render holds no concurrency slot while it waits. The usage limits page explains how to read your limits at runtime instead of hardcoding them.

Plans start at $25/month. Subscriptions from $0.002 per render. image_size goes up to 10,000 px for print-ready listing images.

Upload your t-shirt PSD and check the response for a color smart object next to the print area. Then send each color on that smart object's own entry, exactly as in the request above. The t-shirt mockup use case shows where this fits in a full apparel listing workflow.