Redact a PDF: permanently remove text (not just hide it)
Redacting a PDF means permanently hiding confidential information: a name, an address, an account number, medical data, amounts. The most common — and most dangerous — mistake is to simply draw a black rectangle over the text. Visually the information disappears; technically the text is still there, under the rectangle, and can be copied or extracted in seconds.
Proper redaction removes the underlying data, not just its display. This guide explains the difference, why it has already caused real leaks in official documents, and how to redact a PDF so the removal is truly irreversible — without sending the document to a server.
Why a black rectangle protects nothing
A PDF stacks several layers: text, images, and on top of them, annotations. When you add a black rectangle with a regular PDF reader, you are only stacking an opaque annotation over the text — not deleting it. Anyone can then select the area, copy the hidden content, or extract it with a simple conversion tool. Agencies and law firms have accidentally released names and figures they believed were hidden. The rule is simple: hiding is not deleting.
What irreversible redaction is
Correct redaction does two things: it actually removes the affected text and images from the file's content, then it flattens the page so no recoverable layer remains. The result is a PDF where the redacted area holds no usable data anymore — just a solid block. It is this removal at the data level, not mere visual masking, that separates real redaction from a decorative rectangle.
The method, step by step
Open your document in the Redact tool. Select the areas to hide — words, lines, whole blocks or entire pages. Apply the redaction: the content under those areas is removed, not just covered. Save the new file. Because everything happens in your browser, the sensitive document you redact is never uploaded — this is exactly the kind of task where local processing makes all the difference.
Check that the information is really gone
Never trust your eyes alone. Open the redacted PDF and try to select then copy the hidden area: nothing should come out. Use search (Ctrl+F) on a word you redacted: it should no longer be found. Finally, mind the metadata and the file name, which can also leak information (author, title, original path). A truly cleaned document passes all three tests.