Card Bleed Expander

My partner and I print proxy cards for tabletop games at home. Card images usually come without bleed, the extra margin printers need, so every card had to be extended by hand in an image editor before printing: slow and easy to get wrong.

I built a browser tool that takes the card image and extends its edges automatically. Edges are extended by repeating the outermost row of pixels; for the corners, the tool samples colour along the diagonal towards the centre, so the rounded corners of a card scan fill cleanly instead of leaving white gaps.

Around that core: crop marks, trim and border controls, the standard 63 × 88 mm size, RGB or CMYK output, and batch processing of a whole folder with Save, Save & next or Save all. Everything runs client-side on an HTML Canvas, so card images are never uploaded; the only server code is a small Vercel function for a private feedback form.

A second feature removes the step before that: paste a deck list and the tool downloads the card images directly, for Magic: The Gathering, Pokémon and Yu-Gi-Oh!, ready to be processed and printed. Images come from public card databases: Scryfall for Magic, the Pokémon TCG API and YGOPRODeck.

The first version was a desktop app (.exe / .dmg). When friends with the same problem wanted it, I realised that asking people to install an unknown executable is a real barrier, so I rebuilt it as a web app: nothing to install, and the source is open for anyone to check. I then shared it for free in Reddit communities for home printing.

Two manual steps, finding each card image and fixing its bleed, became one paste and a download. We use it for every print batch, and so do a few friends. The Reddit post got little traction, a useful lesson that building the tool is only half of getting it adopted.