Key takeaways
- Drawing a black shape over text only hides it; the words can still be selected, copied or found by search.
- Proper redaction removes the content under the box, for example by turning the page into an image with the box burned in.
- Check the result: try to select text under each box and search for the words you removed.
- Remember the hidden places: document properties, comments, attachments and other pages.
On this page
Why black boxes leak
A PDF page is built in layers. When you draw a black rectangle in a viewer or editor, it is added as a new shape on top of the text. The words underneath are still in the file. Anyone can select them, copy and paste them, search for them, or simply delete the rectangle. Many published court filings and reports have leaked names and numbers this way.
Redact a PDF in five steps
- Open the Redact PDF tool and choose your file. It is opened in your browser and never uploaded.
- Drag boxes over names, signatures, account numbers and photos. To find text, type it in "Find text to redact" and select Mark all matches, or use the Email addresses and Long numbers buttons.
- Move through every page and check each box covers the whole word, including the first and last letters.
- Select Redact and download. Each page with a box is redrawn as an image with the box burned in, so the content beneath no longer exists.
- Read the check result. The tool opens the new file and confirms that no selectable text remains on the redacted pages.
What a real redaction removes
| Where information hides | Black box in an editor | Redact PDF |
|---|---|---|
| Text under the box | Still there | Removed |
| Images and drawings under the box | Still there | Removed |
| Title, author and other properties | Kept | Not copied |
| Other text on a redacted page | Searchable | Becomes part of the image |
| Pages without boxes | Unchanged | Unchanged, unless you tick "turn every page into an image" |
Check before you share
- Open the redacted copy, press Ctrl + A (Cmd + A on a Mac) on each redacted page and try to copy: nothing should be selected.
- Search (Ctrl + F) for each name or number you removed.
- Look at the pages you did not redact: a name in a header or footer may repeat on every page.
- If the document may contain comments, form fields or hidden layers, tick Also turn pages without redactions into images before downloading.
- Keep the original somewhere safe. Redaction cannot be undone in the copy.
Scanned documents
A scan is already a picture, so there is no text to search. Draw the boxes by hand. The result is the same: the area under each box is painted over in the image itself.
Sources
- Mozilla pdf.js (used to render and read pages)mozilla.github.io
- pdf-lib (used to build the new PDF)pdf-lib.js.org
Written by the Toolkeel team at Sole Digital Media
Fact-checked against the sources above. We test every tool we mention. Editorial policy.
