Why doesn't a black rectangle count as redaction?

A black rectangle is a shape drawn on top of the page. The original text sits in the PDF's content stream underneath — still selectable, searchable, and recoverable by copy-paste. Real redaction removes the underlying content, not just covers it visually. This is the single most common failure mode in high-profile redaction leaks.

Is it safe to use a free online redaction tool?

Only if it processes locally in your browser. If a tool uploads your document to a server before redaction, you've handed the unredacted original to a third party. Browser-based tools that process client-side give you the privacy guarantee redaction requires — verify by checking your browser's network tab during processing for outbound requests.

Does redaction reduce PDF file size?

Usually slightly, since the redacted content is removed and replaced with simple fill blocks. The savings are modest for text-only redactions but can be significant when redacting large images. Running the redacted file through a compressor afterward can shrink it further.

Can redacted content ever be recovered?

Not if the redaction was done correctly. Properly redacted content is removed from the PDF's underlying data structures, leaving nothing to recover. Improperly done "redaction" (black rectangles over text, color-changed text, cropped content) is trivially recoverable. The difference is destructive vs. cosmetic.

Should I also remove metadata when redacting?

Yes. Metadata (author, timestamps, previous filenames, edit history) can reveal exactly what the visible redaction was hiding. Every thorough redaction workflow includes a sanitization pass that strips metadata, either through Acrobat's Sanitize Document feature or by flattening the file.

How to Properly Redact a PDF (2026)

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