Before and after: what a copy-paste reveals
The same line of a bank letter, blacked out two ways. On screen the two results look identical. The difference only shows up when someone selects the line and pastes it somewhere else.
Black box drawn on top
Account holder: — IBAN
Pasted into a text editor:
Account holder: Jane Doe — IBAN DE89 3704 0044 0532 0130 00
Text removed, then blacked out
Account holder: — IBAN
Pasted into a text editor:
Account holder: — IBAN
The left-hand file was not redacted at all. A PDF stores its text separately from what is painted on the page, and a shape drawn on top changes the painting, not the text. The words are still there to be selected, copied, searched for with Ctrl+F, and read by any program that extracts text — including the search engine or the AI assistant your reader pastes it into. Court filings have been published this way, with the “redacted” passages read out by journalists within hours.
Which ways of blacking out leave the text copyable
The 10-second test before you send
Open the exported PDF in an ordinary viewer — your browser is enough.
Press Ctrl+A (⌘A on a Mac) to select all, then Ctrl+C to copy.
Paste into a plain text editor and look for the words you blacked out.
Press Ctrl+F in the PDF and search for one of them as well.
If a blacked-out word turns up in either place, the file is not redacted — do not send it. The copy test only covers the text under the box; metadata, hidden layers and earlier revisions can leak too. Those are covered in what survives a fake redaction, and how to check it.
How to black out text so it is really gone
RedactOffline removes the text under every box when it exports, and it does so in your browser — the PDF is not uploaded anywhere. A free account is required; the free plan covers documents up to 5 pages.
Open your PDF
Go to redactoffline.com, sign in and drop your file in. It is read locally and never leaves your device.
Mark what to black out
Auto-detect finds emails, phone numbers, SSNs, IBANs, card numbers and similar patterns. Names are not auto-detected: draw a box over them, and over signatures, stamps or anything else, by hand.
Export
Each page is rebuilt with the boxes painted in. Only the words outside your boxes are written back as selectable text; a word the box touches is left out entirely.
Run the copy test
Open the exported file and do the select-all, paste and search test above. The blacked-out words should not appear anywhere.
Frequently asked questions
Why can I still copy text after blacking it out in a PDF?
Because the black box was added on top of the text rather than replacing it. A PDF keeps its text and its drawings separately, so covering the text with a shape leaves the characters in the file, selectable and searchable.
Does flattening the PDF fix it?
Not reliably. Flattening merges annotations into the page, but the original text is usually kept underneath. Run the copy test on the flattened file before trusting it.
Can I black out handwriting, a signature or a stamp?
Yes. Draw a box over any area of the page. On export the area is painted black in the page image, so anything visual under it is gone too.
Is the free plan really free?
Yes. The free plan supports documents up to 5 pages, with no credit card. An account is required to use the tool.
Can I undo a redaction after exporting?
No — that is the point. The exported PDF contains nothing under the boxes to restore. Your original file is never modified, so keep it if you may need it later.
Black out text that stays blacked out
The text under every box is removed on export. Nothing is uploaded. Free plan up to 5 pages.
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