The short answer
Open the PDF in the tool below. To hide a specific area, drag on the page to draw a box. To hide every occurrence of a name or number, type it in the search field (one entry per line), tick ready patterns such as Email addresses or IBANs if you need them, and press Find and mark. Check the boxes on each page, then press Apply redactions.
The tool saves every page that has a box as an image with the boxes painted in, copies the other pages unchanged and builds a new file without document information, bookmarks, comments or attachments. It then reads the new file again and tells you whether any searched text can still be found. Download it only when that check is green.
Try it here: Redact PDF
Open the full tool pageWhy a black box is not a redaction
A PDF page is a list of drawing instructions: put this text here, draw this image there. When you add a black rectangle in an editor or a viewer, a new instruction is added on top. The text underneath is still in the file. Anyone can select it, copy it, search for it or extract it with a free tool, and some viewers even show it when the page loads slowly.
This mistake has exposed court documents, government reports and company files many times. The same is true for highlighting text in black, changing the text color to white, or covering it with a black image. Real redaction means the original content is gone from the file.
- Drawing a black rectangle: the text is still underneath.
- Black highlighting or black text color: the text is still there, only colored.
- Placing an image over text: the text is still underneath.
- Cropping the page: the content outside is hidden but still in the file.
- Proper redaction: the content under the box is removed from the file.
How this tool removes the content
There are two ways to remove content from a PDF. One is to edit the page instructions and delete the text, images and drawings under each box. This is what professional tools try to do, but PDFs store text in many ways, and a missed character or a glyph split across two instructions can leave part of a word behind. The other way is to replace the page with an image of itself in which the boxes are already black. Nothing of the old page survives, because the old page is no longer in the file.
This tool uses the second method because it is reliable for every kind of PDF. Only pages with at least one box are converted. You choose the quality: 200 DPI keeps normal text sharp, 300 DPI suits small print and documents you will print, and 150 DPI gives a smaller file. Pages without boxes are copied as they are, with selectable text and working links.
| What | Pages with boxes | Pages without boxes |
|---|---|---|
| Text under the box | Removed | Not affected |
| Other text on the page | Becomes part of the image, not selectable | Stays selectable |
| Links | Removed | Kept |
| Comments and attachments | Removed | Removed |
| Title, author and XMP metadata | Removed from the whole file | Removed from the whole file |
Finding every occurrence
Manual boxes are fine for a signature or a photo, but names and account numbers often appear many times. Type each term on its own line. Spaces are flexible, so a name broken across two text pieces is still found, and case is ignored unless you tick Match case. Ready patterns find email addresses, phone numbers, IBANs and card numbers. IBANs are checked with the IBAN checksum and card numbers with the Luhn algorithm, so an invoice number or a date is not marked by mistake.
After the search, the result line shows how many matches were marked and on how many pages, and each page thumbnail shows its number of boxes. Go through the pages: you can move a box, resize it from its corner, delete it with the cross or the Delete key, and draw extra boxes for anything the search could not know about, such as a signature, a stamp or a face in a photo.
Scanned documents
A scanned page is a picture of paper. It has no text layer, so a search finds nothing and the tool tells you so. You can still redact it by drawing boxes by hand. If the document is long, run it through the OCR tool first to make it searchable, then use Find and mark on the result. Check the boxes carefully, because OCR can misread characters.
Check before you share
When the new file is ready, the tool opens it again with a PDF reader and checks two things: the redacted pages contain no text at all, and none of your search terms can be found anywhere in the file. If you removed or moved a box so that a match is no longer covered, it says how many matches are still visible. Fix the boxes and apply again.
It is still worth opening the downloaded file yourself. Zoom in on each box, try to select the text around it, and press Ctrl+F (Cmd+F on a Mac) to search for a name you redacted. Keep the original file in a safe place, because a redacted copy cannot be turned back into the original.