How to remove personal information from a PDF before you share it

Sending a bank statement to a landlord, a medical record to an insurer, or a contract to a colleague often means hiding part of it first: an account number, a Social Security number, a home address, someone else's name. The obvious way to do it is also the way that fails most often.

Why a black box is not enough

Drawing a black rectangle over text in a PDF hides it from view, but the text is still in the file underneath. Anyone can select it and copy it, or open the file in another program that ignores the rectangle. This has embarrassed law firms and government agencies more than once: documents released "redacted" whose secrets anyone could copy and paste.

Redact it properly

1. Open Redact PDF and choose your document. It stays on your device.
2. Mark everything you want gone: search for a name or number to mark every place it appears, use a ready-made search for emails, phone numbers and the like, or drag boxes over any area by hand.
3. Download the redacted copy.

Each page with a redaction is rebuilt as an image with the boxes burned in, so nothing under a box survives in any form: not as text, not as a hidden layer. Pages you didn't redact are copied across untouched, so their text stays selectable.

The redacted file is also built fresh, so it doesn't carry over the original's title, author, bookmarks, attachments or scripts, any of which can repeat the very thing you hid.

Check before you send

• Open the redacted copy, select all the text on a redacted page (Ctrl+A, or Cmd+A on a Mac) and paste it somewhere. Nothing from under the boxes should appear.
• Search the redacted copy for the name or number you removed.
• Look at the whole page, not just the first instance: the same number often appears in a header, a footer or a second table.

The hidden information: metadata

PDFs also carry information you never see on the page: the author's name, the software and computer that made it, creation dates, sometimes the original file name. To see it, and change or blank it without redacting anything, use Edit PDF metadata. If a form still has fillable fields you don't want changed, Flatten PDF makes the filled-in values a permanent part of the page.

Redacting is exactly the job you shouldn't do on someone else's server: the whole point is that the information must not travel. Filezuma's redaction runs entirely in your browser.