Endpoint guide / POST /sticker

Create die-cut stickers with one API call

The sticker endpoint isolates the subject, adds a clean outline, and returns a transparent PNG ready for chat, social, or product UI.

Original dog photo before sticker processing — Input

Dog photo converted to a die-cut sticker with a white outline — Output

Working request

Configure the edge, not a design pipeline.

The endpoint returns a transparent PNG. Adjust the stroke and padding in the same multipart request, then store or deliver the returned bytes.

cURL

curl -X POST "https://useknockout--api.modal.run/sticker" \
  -H "Authorization: Bearer $TOKEN" \
  -F "file=@portrait.png" \
  -F "stroke_width=24" \
  -F "stroke_color=#FFFFFF" \
  -F "padding=32" \
  -o sticker.png

Good uses

User-generated sticker packs for chat and community products
Creator thumbnails, reaction assets, and social overlays
Product badges and cutout treatments inside an editor

Production checklist

Use PNG when you need a transparent background.
Increase padding when the outline feels cramped near the canvas edge.
Choose a stroke color that stays visible on both light and dark surfaces.
Keep the API token on your server, never in browser code.

Build with the endpoint

Start with 30 images every month.

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