Guide · 2 min read
How to hide personal data in a PDF before sending it
Black out your ID number, bank account or address safely. Why a black box isn't always enough and how to do it properly.
You're asked for an invoice, contract or payslip, but there's data they don't need to see: your account number, ID, address or salary. Hiding it is good practice, as long as it's done properly.
The most common mistake: a black box on top
Many people draw a black rectangle over the data with a PDF editor or Word. It looks covered, but the text is still underneath: selecting and copying it, or opening the file in another program, is enough to read it. It has happened even with court and government documents.
How to do it properly
For the data to truly disappear, the redacted page has to be turned into an image after covering it. That way there's no text underneath to recover. That's what the Redact tool does:
- Open Redact and choose the PDF.
- Tick what to look for: ID numbers, bank accounts, cards, emails or phone numbers, or type specific words such as your name or street.
- Click “Find and redact” and check every page.
- Redact anything missed by dragging across the page.
- Click “Redact and download”.
Check the result
- Open the downloaded PDF and try to select the redacted text: it shouldn't be selectable.
- Use the PDF reader's search (Ctrl+F) for the hidden data: it shouldn't find it.
- Also check headers and footers, where data is often repeated.
Tip: Automatic search finds data written as text. Scanned documents have no text to search, so you'll need to redact by hand.
What data to hide
It depends on what the document is for, but as a rule: hide everything the other person doesn't need. For example, to prove you paid an invoice they don't need to see your full account number, and to prove income the total is sometimes enough, without the payslip details.