Placing a black box over sensitive text doesn't redact a PDF — the data stays in the file. Learn how to permanently remove information from PDFs, which tools actually work, and how to verify your redaction held.
Frequently Asked Questions
What is the difference between redacting and hiding text in a PDF?
Redacting permanently removes content from the PDF's internal structure, making it unrecoverable. Hiding (placing a black box over text) only covers it visually — the original text stays in the file and can be revealed by copy-pasting, searching, or simply deleting the annotation overlay.
Can redacted text in a PDF be recovered?
If proper redaction tools were used — such as Adobe Acrobat Pro with Sanitize enabled — no, the data is permanently deleted. If a black box or drawing tool was used instead, yes: the underlying text is still in the file and trivially recoverable by copy-paste or text extraction.
How do I redact a PDF for free?
PDF24's free online tool permanently removes content by converting pages to raster images, leaving no text layer to extract. iLovePDF and SmallPDF also offer free redaction. For legal or medical documents, Adobe Acrobat Pro remains the most reliable option.
Is Mac Preview safe for redacting PDFs?
No. Preview cannot remove the underlying text layer — it only adds a visual overlay. In some PDF viewers, hovering over the "redacted" area still reveals the hidden content. Never use Preview for sensitive document redaction.
How do I verify my PDF redaction worked?
Try to copy-paste text from the redacted area, search for the removed words in your PDF viewer, and check the document's metadata for sensitive information. If all three show no trace of the original content, the redaction was successful.