How to Redact a PDF Properly (Why Black Boxes Can Fail)
Redaction goes wrong more often than people think. A black rectangle drawn over a name with an ordinary annotation or highlight tool hides it on screen, but the text is often still in the file: anyone can select it, copy it, or delete the box. Court filings and government reports have leaked this way. Proper redaction removes what is under the box. This guide shows how to do that, and how to check the result.
Why a black box is not enough
A PDF page is built in layers. Drawing a shape adds a new layer on top, while the text below stays where it was. Search, copy and paste, or a screen reader can still reach it, and anyone with a PDF editor can move the shape away.
A real redaction removes the content itself. HuntPDF does this by turning each redacted page into an image when you download, so the covered words are gone, not just hidden. The rest of the document is unchanged.
Redact by hand
Open Redact PDF and drag a box over each item to hide: an account number, a signature, a home address, a photo. To hide every copy of a word or number, press Ctrl+F (Cmd+F on a Mac), search for it and choose Redact all. Scanned pages are pictures, so search will not find words in them; draw those boxes by hand.
Let AI find personal details
On a long document, AI Redact PDF can look for names, email addresses, phone numbers, ID numbers, card numbers, IBANs and postal addresses, and black them out for you. Pick the kind of detail to find, then read the result. If it missed something specific to your document, such as a case reference or staff number, take the file into Redact PDF and cover it by hand.
Clean the hidden data too
The visible page is not the only place information hides. A PDF also stores metadata such as the author's name, a working title and the software that created it. Run the redacted file through Remove PDF Metadata before sharing it. If the file contains form fields or comments, Flatten PDF fixes them into the page so nobody can edit them afterwards.
Check before you send
Open the redacted file and try to select the text where a box is. You should not be able to. Search for a redacted name or number: it should not be found. Scroll every page, including headers, footers and small print, which are easy to miss.