How to redact a PDF properly

Updated 26 October 2026 · from SiteHelm

Redacting means removing information before a document is shared. The mistake people make is hiding it instead of removing it.

Covering isn’t removing

Drawing a black box over text, changing the text to white or highlighting it in black all change what you see, not what’s in the file. The words are often still there, and can be copied, searched for or read by software. Government guidance on publishing information safely warns that information hidden this way “is at risk of unintended disclosure if the electronic version is distributed”.

Check for hidden data

A file can hold more than shows on the page: comments, earlier versions, hidden layers, form fields and document properties such as the author. Pictures can carry the date, the device and where they were taken. Check for these before sending.

A safe way to do it

1. Work on a copy, never the original.
2. Use Find to track down every place the name or number appears.
3. Redact with a tool that removes what’s underneath, not one that draws a box on top.
4. Open the saved file and try to select, copy and search for what you removed.
5. Have someone else check it if it matters.

In this editor, a page with redactions is rebuilt as a picture with the areas blacked out when you save, so the original text and drawing on that page aren’t in the new file.

Open the editorFree. No sign-up. Nothing is uploaded.