Secure PDF redaction
Redact PDFs so the original content is gone, not just hidden. Black-rectangle overlay + flatten produces unrecoverable redaction.
'Redaction' has a wide spectrum of strength. The weakest version — highlighting text in black ink in a PDF reader — leaves the underlying text fully intact in the file structure; anyone can copy it. The middle version — placing a black rectangle on top of the text — looks redacted but the text is still in the file, recoverable by copy-paste, file inspection, or text extraction tools. The strongest version — actually removing the text data from the PDF — is what regulators, lawyers, and security teams mean by 'real redaction'.
PDFOnly's secure redaction workflow: place black filled rectangles over sensitive areas via Edit PDF, then run Compress PDF (high preset) which rasterizes the page region and eliminates the underlying text data from the file structure. The result is a redacted PDF where the original text isn't recoverable through any standard means. Verify by trying to copy from the redacted areas — you should get either nothing or just the text 'image' (pixel data, not the original characters). For absolute audit-grade compliance, pair this with a redaction-verification tool that explicitly inspects the file for residual sensitive data.
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Frequently asked questions
How is this different from just adding a black rectangle?
Adding a rectangle alone leaves the underlying text in the PDF file structure — anyone can copy from beneath it. The compress step that follows is the critical part: it rasterizes the page (or that region of it), which destroys the text layer. Combined, you get redaction where the text is gone, not just visually hidden.
Is this redaction strong enough for legal filings?
For most internal redaction (HR document sharing, basic FOIA responses, removing customer details from a case study): yes, sufficient. For high-stakes legal redaction where opposing counsel may inspect the file forensically: pair with a redaction-verification tool that explicitly checks for residual data, or use Adobe Acrobat's built-in redaction feature which removes objects from the PDF structure directly.
Will the redacted areas survive being printed and re-scanned?
Yes — the black rectangles are part of the page content. Print and scan, the redacted areas remain black. The underlying text was destroyed in the compress step, so there's nothing to leak even if someone OCRs the print-out.