Crop PDF

I built this after getting tired of scanned PDFs with an inch of dead scanner-bed gray around every page. It happens constantly with flatbed scans and with phone-scanning apps that don't quite trim the frame — you end up with a document that looks unprofessional even though the content itself is fine. Crop PDF exists to fix exactly that: drag a box over the page, see the result live, and trim it without re-exporting the whole document somewhere else.

How it works

This is the part people usually get wrong in their head: cropping a PDF does not delete anything. What actually changes is the page's CropBox — a rectangle stored in the PDF's page dictionary that tells viewers "only show this part." The original content (the MediaBox, and everything drawn on the page) is still sitting there underneath. That's why you can crop, download, re-open the file in this tool, and pull the crop box back out to recover the "hidden" area — nothing was thrown away.

Practically, this means two things. First, there's essentially no quality loss from cropping itself — you're not re-rasterizing images or re-compressing text, you're just changing which rectangle gets displayed. Second, file size barely moves. People expect a crop to shrink the file the way trimming a photo does, and it mostly doesn't, because the full-resolution content is still embedded. If your actual goal is a smaller file, crop first for appearance and then run it through compression separately — they're solving different problems.

A real example

Say you scan a receipt on a flatbed scanner set to A4, and the receipt itself only covers the top third of the page — the rest is gray scanner glass. Original page is 210 × 297mm. You drag the crop box down to roughly 210 × 90mm around the receipt, apply it to that one page, and download. Open the result and the visible page is now just the receipt — but if you check the file in a PDF inspector, the MediaBox is still 210 × 297mm and only the CropBox changed. Print it and most printers respect the CropBox and print just the receipt; a few older print drivers ignore it and print the full original page. That inconsistency is the single most common complaint I get about cropping tools in general, not just this one.

Where people get this wrong

• Expecting a smaller file. Covered above, but it's worth repeating because it's the #1 support question — cropping ≠ compressing.
• Cropping one page and assuming it applies to all of them. If your scan has inconsistent margins page to page (very common with stapled documents scanned in batches), "Apply to All Pages" with one crop box will clip content on pages where the margin was smaller. Check a few pages spread through the document before you commit to all-pages.
• Assuming the crop is destructive and safe to rely on for redaction. This is the one that actually matters. Because the original content is still embedded under the CropBox, cropping out a name, signature, or account number does NOT remove it from the file — anyone who opens it in a different tool and resets the crop box can see it again. If you need to permanently black out content, that's a redaction/flattening job, not a crop. I get asked about this often enough that it's worth stating plainly here.