How to redact a PDF on a Mac (and why drawing a box isn't enough)

The short answer

Open the PDF in a browser tool that rebuilds each page without the covered text, such as Redact PDF, then test the result by trying to copy the hidden words. It's free, needs no account, and works in Safari, Chrome or Firefox on any Mac.

Drawing a black box is not redaction

PDF viewers usually let you add shapes, highlights and comments. A filled black rectangle looks like redaction, but it's normally saved as an annotation on top of the page. The text beneath is still part of the file, so it can show up when someone copies, searches, or opens the PDF in a different program.

Real redaction removes the content itself. The simplest way to be sure is to flatten the page into an image, so there is no text left to find under the box.

Redact a PDF on your Mac

1. Open Redact PDF and drag the PDF from Finder onto the page.
2. Review the highlighted emails, phone numbers, account and ID numbers, and labelled names and addresses.
3. To hide a word everywhere it appears, use Find and redact: type it once and every match on every page is covered.
4. Drag boxes over anything else, such as signatures, logos or photos.
5. Export. Pages are rebuilt from pixels, metadata is removed, and the output is OCR-read again so anything still legible is flagged before you download.

You can also paste a screenshot straight into the editor with Cmd+V, which is handy for a single page.

Check before you send

Open the redacted file, select the area you covered, copy, and paste into a text editor. Then search the PDF for a word you hid. If neither finds anything, it's gone. For a fuller test, including metadata and comments, use the PDF Redaction Checker.

If someone sends you a PDF they redacted with a viewer, it's worth checking too. See how to check if a PDF is redacted and free Adobe Acrobat redaction alternatives.