The mistake that exposes sensitive data
If you place a black rectangle or a highlight over text in a PDF editor, the original text is still inside the file. Anyone can select the area, copy it, and paste the hidden text somewhere else.
This has caused real leaks of documents that were supposed to be protected. A redaction that can be undone with copy and paste is not a redaction.
Covering text only changes how a page looks. Real redaction changes what the file contains.
What proper redaction does
A reliable redaction removes the underlying content, not just its appearance. In practice that means one of the following:
- The text under the marked area is deleted from the file
- The page is flattened into an image with the marked area blacked out, so no text layer remains
Flattening is simple and dependable, though the pages stop being searchable. That is usually an acceptable cost for a document containing sensitive information.
Don't forget metadata
Author names, titles, comments and document properties can also reveal information. Check these before sharing a file.
How to redact a PDF in your browser
- Open the PDF redactor and choose your file. It stays on your device.
- Draw a box over every piece of information you want removed.
- Review each page. Missing a single instance of a name is easy on long documents.
- Apply the redactions and download the result.
- Verify the output using the checklist below before you share it.
How to verify a redaction worked
Never trust a redacted file until you have tested it:
- Try to select the redacted area with your cursor and copy it somewhere else
- Use the search function to look for a word that should be gone
- Open the file in a second PDF viewer to compare
- Check the document properties for names and titles
If any of these reveal the original information, the redaction failed and you should not share the file.
Why redacting locally matters
Redaction is mostly done on documents that are already sensitive: contracts, medical letters, legal paperwork, IDs. Uploading the unredacted file to an online service to remove the sensitive parts defeats the purpose.
When redaction runs in your browser, the original never leaves your device. Only the redacted copy is ever shared.
Frequently asked questions
Is a black rectangle enough to redact a PDF?
No. The text underneath usually remains and can be copied. Proper redaction removes the underlying content or flattens the page.
Can a redaction be reversed?
A correct redaction cannot be reversed, because the information is removed. That is also why you should keep the original file somewhere safe.
Do I need to redact images and scans too?
Yes. Information in a scanned image is part of the picture, so it must be blacked out in the image itself rather than just covered.
Redact a PDF in seconds
No upload, no account. Your file never leaves your device.