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The Customei editor is fast — but like any canvas app, it has practical limits. Following these guidelines keeps the editor responsive, the storefront snappy, and your print files clean.

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Layer count

  • Recommended: under 100 layers per template.
  • Typical template: 10–30 layers.
  • Above 150: you may notice the editor slow down on dragging and selection.
If you need more layers, consider grouping decorative elements into a pre-flattened image (export a group of shapes as a single PNG and add that as an image layer).

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Canvas size

  • Design at the final print resolution. Scaling up at publish time introduces blur.
  • At 300 DPI, most products land between 1500 × 1500 and 4000 × 4000 px. Much larger than that and you’ll feel the editor slow down during zoom and pan.
  • If your product needs a truly massive output (billboards, banners), split it into tiles and generate each tile as a separate template.

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Image size

  • Customer uploads: allow up to the cap set in the option set field (default is merchant-configurable, typically around 10 MB per file).
  • Library images: no hard cap, but anything above 5000 px on the longest side is usually overkill. Customei downscales to the target print resolution at publish time.
  • SVG: use for simple, sharp vectors (logos, icons). Avoid for complex illustrations — the storefront rasterizer is simpler than a full SVG engine.

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Fonts

  • Upload .woff2 when you can — it’s the smallest format and loads fastest on the storefront.
  • .ttf and .otf are accepted but larger.
  • Keep your library’s active font count modest. Each font adds to the storefront bundle; 3–5 carefully chosen fonts are plenty for most brands.

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Text layers

  • Set a character limit on option-set text fields. Long customer inputs blow up the canvas and make the print unreadable.
  • Curved text breaks down at extreme radii — test every curve on a mockup.
  • Warped text is expensive to re-render on every keystroke. For fields that change often (e.g. customer name), prefer regular text + tint, not warped text.

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Image quality vs bundle size

Every image you add to a template ships in the published bundle. To keep product pages fast:
  • Prefer shared library assets. Images reused across templates dedupe in the bundle.
  • Compress before uploading. PNG-8 or WebP for clipart, JPG for photos.
  • Transparent PNGs are fine — just don’t oversize them. A 4000 × 4000 PNG for a small icon is wasteful.

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Storefront performance

  • First paint on the storefront is faster when the bundle is smaller. Audit big templates: do you really need that 8 MB PSD-style PNG?
  • Option fields that mutate many layers on every keystroke (e.g. a text field that drives three separate layers) are the most common cause of lag. Prefer fewer bindings per field when possible.
  • Background removal on uploads adds 2–5 seconds per upload — test on slow connections.
  • Transparent areas in an image layer print white (or your product’s base color). Test on the mockup.
  • Thin strokes (< 2 px at 300 DPI) may vanish on some print processes. Use a minimum 2 px stroke for any outline you want visible.
  • Small text (< 6 pt at final size) is unreadable on most print media. Set a floor on your option-set text fields.

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When in doubt

  • Test on a real mockup before publishing.
  • Place a test order before handing over to a customer.
  • Download the print file from an order and open it in an image viewer; if it looks wrong there, it’ll look wrong on the product.

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