How to check if a PDF is properly redacted
Four quick tests to see whether a redacted PDF still hides text under its black boxes, plus metadata, comments and form fields. Free, and nothing is uploaded.
Updated · 2 min read
Do it now: free, in your browser, nothing uploaded.
Open PDF Redaction CheckerThe short answer
Drop the PDF into the PDF Redaction Checker. It looks for text still present in the file's text layer under boxes, and lists metadata, comments, form fields and attachments. It runs in your browser, so the PDF isn't uploaded.
If you'd rather check by hand, the tests below take a couple of minutes.
Four manual tests
- Copy and paste. Select across a blacked-out area, copy, and paste into a plain text editor. If words appear, they weren't removed.
- Search. Use the viewer's search for a word or number you know was hidden. A match means it's still in the file.
- Zoom right in. Look at blurred or pixelated areas at high zoom. Light blur over short numbers can sometimes still be read or guessed.
- Open document properties. Check the author, title and other fields for names or details that shouldn't be there.
If copy and paste brings back text, don't just fix the box. Redact the original again with a tool that removes the content, then test again.
What the checker looks for
| Check | Why it matters |
|---|---|
| Text under boxes | The most common failure: a box drawn on top of words that stay in the file |
| Metadata | Author names, titles and software details |
| Comments | Review notes can quote the hidden text |
| Form fields | Typed values can survive even when a page looks blank |
| Attachments | An embedded original can undo every box |
A clean result means the checker found none of these. It can't judge whether you hid the right things, so still read the pages yourself.
Pay attention to what's left visible around a box, too. A covered name next to an uncovered signature, email address or job title may still identify the person, and a total that equals the sum of visible rows can give away a hidden amount.
If the PDF fails
Open it in Redact PDF, cover what needs hiding, and export. The pages are rebuilt from pixels, so nothing remains under the boxes, and metadata is removed. The export is also read again with OCR to flag anything still legible, such as a number left outside a box.
For why some redaction methods fail in the first place, see how to blur text in a PDF and can blurred text be unblurred?
Questions
Can the checker read scanned PDFs?
A scanned page is an image with no text layer, so there's no hidden text under boxes to find. Read scanned pages carefully by eye instead.
Can I check a PDF someone else sent me?
Yes. The file is checked in your browser and isn't uploaded, so you can safely test a document before forwarding it.