100% In Your Browser · Zero Uploads · Instant Results

Four tools.
One workflow.

Drop your print file once. Toggle any combination of tools to instantly check resolution, simulate CMYK color shift, hunt stray pixels, and visualise bleed and safe zones — all running locally in your browser with no server, no account and no waiting.

Open Print Prep
The workflow

Ready in three steps

01

Drop your file

Drag and drop or click to browse. Accepts PNG, JPG, TIFF and WebP up to 200 MB. Your file is read by the browser's FileReader API — it never touches a server.

02

Toggle your tools

Use the side panel to turn on any combination of the four tools. Each runs independently — enable one or all four at the same time.

03

Read the results

Get instant, actionable feedback in the canvas and sidebar panels. Fix issues in your design tool, then re-drop the corrected file.

The tools

What each tool does

Tool 01

True DPI Checker

Most design apps show you the DPI stored in the file's metadata — but POD printers don't care about that number. They care about pixel count ÷ print size. This tool calculates the real effective DPI for your exact product dimensions.

How it works
  • Select a product preset (T-shirt, poster, mug wrap, etc.) or enter custom dimensions
  • The tool divides your pixel dimensions by the print size to get width-DPI and height-DPI
  • It flags the limiting axis (worst-case DPI) and maps it to a traffic light: green ≥ target, yellow 70–99%, red < 70%
  • A gauge bar and "max safe size at 300 DPI" help you understand the tradeoff
Common findings
✅ Print-Ready — meets or exceeds the minimum DPI for this product
⚠️ Acceptable — within 70% of target; slight softness possible
🚫 Too Low — customers will see pixelation; upsizing required
Pure client-side math No canvas or worker needed. All computation runs synchronously from the pixel dimensions already stored in state.
Tool 02

CMYK Reality Check

Monitors, phones and design apps show colours in RGB — a light-based colour space that can display vivid neons and out-of-gamut colours that ink simply cannot reproduce. This tool simulates what those colours will look like after conversion to the CMYK ink model used by most offset and sublimation printers.

How it works
  • Your image is decoded to raw pixel data via an offscreen canvas
  • A Web Worker runs a CMYK gamut-compression algorithm on every pixel in a background thread, keeping the UI responsive
  • The result is painted onto a second canvas, layered behind a draggable divider
  • Drag the slider left and right to compare RGB (left) vs. CMYK simulation (right) at any split point
Most affected colours
Neon green → olive
Hot magenta → burgundy
Electric blue → dark steel
Background thread processing Pixel simulation runs in an inline Web Worker (Blob URL — no import issues in Astro). Progress is reported via postMessage so the sidebar stays live during processing.
Tool 03

DTG Stray Pixel Finder

DTG (Direct-to-Garment) printers spray white ink underbase wherever a pixel has any opacity. Semi-transparent pixels around your design's edges — left over from feathered selections, AA anti-aliasing, or a JPG save — cause a visible white halo on dark shirts. This tool finds every pixel with alpha between 1 and 254.

Two view modes
  • Background injection — paints a solid colour (neon magenta, hot green, black, white or grey) behind your image so semi-transparent fringes are immediately visible
  • Highlight mode — replaces every stray pixel with neon yellow while leaving the rest of the image intact, making the exact problem pixels unmissable
Severity breakdown
Ghost (α 1–63) — almost invisible, high underbase risk
Quarter (α 64–127) — light halo on dark shirts
Half (α 128–191) — noticeable fringing
Near-opaque (α 192–254) — visible as blended colour cast
Fix in Photoshop Select → Color Range → Sampled Colors on the transparent area, expand by 1–2 px, then Delete. Re-export as PNG with transparency.
Tool 04

Safe Zone Overlay

Every POD product has a print boundary, a bleed / wrap zone that gets folded or trimmed, and a safe zone where your text and key art must stay to survive the finishing process. This tool overlays both zones directly on your image at accurate proportions.

How it works
  • Pick a product template from 10 presets covering apparel, wall art and accessories
  • Your image is scaled to the product's print aspect ratio so the overlay is geometrically accurate
  • Toggle the red bleed/wrap zone and the green safe zone on or off independently
  • A bottom bar shows the exact print dimensions for the selected template
Available templates
👕 Apparel T-Shirt Full Front, Hoodie, All-Over Print
🖼️ Wall Art Poster 11×14, Poster 18×24, Canvas 12×12 Gallery Wrap
🎒 Accessories Phone Case, Tote Bag, Mug Wrap, Sticker
Pure CSS overlay No canvas — zones are rendered as absolutely-positioned <div> borders over the <img> tag, so they're crisp at any zoom level.

Your file never leaves your browser

Print Prep has no backend. There is no server that receives your image, no analytics that log your filenames, and no CDN that caches a copy. Everything — file decoding, pixel analysis, canvas rendering, DPI maths — runs inside your browser tab using the FileReader API, Canvas API, and Web Workers. When you close the tab, everything is gone.

Read the full privacy policy →

Ready to check your file?

No sign-up. No install. Just drop your image.

Open Print Prep