How to Properly Redact PDFs on Mac: Remove Sensitive Data for Good

How to do it

1. Open the PDF in Preview (double-click usually does it).
2. Click the Markup toolbar → select Redact (black rectangle icon).
3. Highlight the text or area you want to redact.
4. Make a copy of the original first if you need to keep an unredacted version.
5. Save and close the document. Closing makes the redaction permanent and it can no longer be undone.

Why this matters

If you just draw a black rectangle over text, the underlying data stays in the PDF file and can be extracted with simple tools. The Redact tool removes content from the file structure itself.

Good to know

• Metadata (author, creation date) isn't automatically removed — clean that up separately if needed.
• Table-of-contents entries that point to redacted text may remain and need a separate check.
• For complex PDFs (form fields, embedded objects), double-check with a professional tool.
• Especially important for lawyers, government agencies, and anyone handling confidential documents.