Add bleed and crop marks

Three millimetres is the default here and the figure most commonly requested across European and much of the US commercial print market, but the only authority is your printer's own spec sheet. The Bleed size field accepts 0 to 30 mm, so 5 mm, or a wide 10 mm for a heavy board job, are one keystroke away. Larger bleed is not automatically safer: it grows the sheet and the file, and some layouts have nothing useful to put in the extra band. Mark length is a separate field, 1 to 30 mm and defaulting to 5, and it controls only how long the crop-mark hairlines are — not how much of the page gets cut off. Changing either one redraws the preview immediately, so you can see the finished slug before writing anything.

The tool declares and reserves the bleed area — it does not invent artwork to fill it. Your page becomes the TrimBox and the BleedBox is drawn around it at the distance you set, but nothing stretches your background outward, so if your design's colour or image stops exactly at the trim edge, the bleed band comes out white and a slight misregistration at the guillotine will still show a white sliver on the finished piece. Extend backgrounds past the trim edge in your design application before exporting. One case does fill itself: if the source PDF already carries artwork outside its visible crop area, that hidden material becomes visible in the new bleed band, because the enlarged sheet no longer clips it away.

All five page boxes are rewritten, so none of them can be left stale. The TrimBox becomes your original visible page — the CropBox intersected with the MediaBox — which is the final cut size. The BleedBox is that trim grown by your bleed value on all four sides. The MediaBox and the CropBox both become the slug sheet: large enough to hold the bleed plus the marks plus a hairline of padding, so a conforming viewer or RIP clips nothing off. The ArtBox is carried over from the source and clipped to the new sheet, or falls back to the trim if the source had none. Your artwork is translated into position on the bigger sheet, and any annotations are moved by the same vector so they stay attached to what they annotate.

The sheet gets bigger and nothing is scaled or cropped. Each page grows outward by the bleed on every side plus a few millimetres of room for the marks, and your artwork is translated to sit centred on the larger sheet at its original size — an A4 design comes back on a slightly larger sheet that still carries an A4 TrimBox. That is why the result is not the file you hand a client as a finished document: on screen it shows the page floating in white with cut marks around it. The live preview mirrors the export exactly, using the same geometry, so the trim area, the tinted bleed band and the hairlines in the slug are where they will be in the PDF.

What a print shop needs is usually more than marks, and this tool covers only part of it. It gives you correct TrimBox and BleedBox geometry plus crop marks and optional registration crosshairs, which is what most "send us a PDF with bleed and trim marks" requests are actually about. It does not convert colours to CMYK, embed an ICC output intent, add colour bars or slug text, set overprint, or verify that your fonts are embedded — and the marks it draws are plain black rather than a four-plate registration black. Send the file to your printer and ask them to preflight it. If they come back asking for CMYK or a specific output intent, that conversion has to happen in your design application, not here.

The tool is free and unlimited, adds no watermark, and your artwork never leaves the browser. Pages are read from your disk, the boxes and hairlines are written with pdf-lib in memory, and the result goes straight to your downloads — there is no upload step, no queue and no copy retained anywhere, because the page has no backend to retain one. For packaging comps, unreleased campaign artwork and anything under NDA, that is a meaningful difference from a service that processes your file on someone else's machine. Only the crop marks, registration marks and box definitions you asked for are added; nothing else in the file is touched, and existing annotations move with the artwork rather than being dropped.