How to redact a PDF properly

The two-minute test

Before you trust any redacted PDF, including one somebody else sent you, try to get the text out.

1. Open the file in a PDF reader or a browser.
2. Press Ctrl+F (Cmd+F on a Mac) and search for a word that should be hidden.
3. Select the blacked-out area, copy it, and paste it into a text editor.
4. If the word turns up anywhere, the redaction is only cosmetic.

The test needs real text in the file. A scanned page is a picture, with no text to search or copy, so the test proves nothing there. Look at the page itself instead.

Redacting so the text is gone

Redact Content removes what is under each box from the file instead of covering it. It runs in your browser, so the document stays on your device, which is the point when the file is confidential. Expect the finished area to be blank rather than black, so check the result by eye.

1. Open your PDF in Redact Content.
2. Draw a box over each piece of text or image you want gone.
3. Apply the redactions.
4. Download the result and keep your original somewhere safe.

Applying is permanent. The text and images under each box are removed from the page, so work from a copy. If you miss a spot, start again from the original.

Text under a box is removed. An image or a drawing that a box touches is removed whole, even if the box covers only a corner of it. On a scanned page, which is one big picture, that means the whole page goes blank. Redaction suits PDFs with real text. For a scan, black out the paper copy before you scan it.

Text that repeats

A name that appears in the header of every page is easy to miss once. Find & Redact takes the text you type and removes every occurrence in one pass. It matches the literal text and ignores capital letters. It does not understand patterns, so it cannot find "any phone number" for you, and a short entry can match inside a longer word. Type a whole word when you mean a whole word. On a scanned page it finds nothing, because there is no text to match.

Redaction is not the same as cleaning

Redaction deals with what is on the page. The same words can also sit elsewhere in the file: in the document title and other metadata, in bookmark titles, and in the hidden text some PDFs carry for screen readers. Sanitize PDF clears metadata, scripts and attached files, and the metadata guide explains what it does and does not remove. Check the bookmarks and the title yourself.

Check your own work

Run the two-minute test on the exact file you plan to send, not on the one you started with. It takes less time than the redaction did.

Redact Content and Find & Redact are Pro tools, and each has one free trial. The trial output is watermarked, so use it to test the tool on a real file, not to send the result. The Pro page has the details.