> guide redact-pdf
Redact a PDF properly
Names, amounts, account numbers: you need to take something out of a PDF before it is passed on. This is how it really disappears instead of just being hidden.
Last updated: · 4 min read
In short
- A bar that you place over the text in a writing or drawing program only hides it. The text is still in the file.
- In “Redact PDF” the page is redrawn as an image and the bars are painted into that image. After that there is no text left at that spot.
- Look at the finished file and double-check it with “PDF metadata” before you send it.
The most common mistake when redacting is a black rectangle on top of the text. On screen it looks done. But the file still contains the text: anyone who selects the spot, copies it or lets software read the file gets it back. The same goes for a black highlighter drawn across the line. What matters is not how the page looks, but what is stored in the file.
How to do it
-
Mark the spots
Open the PDF and go to the first page with something confidential. Drag a rectangle with your mouse or finger over every spot that should disappear. You can mark as many spots as you want on each page, and across several pages. Without a mouse, “Add box” places a box in the middle that you move with the arrow keys. Hold Shift to resize it. Under “Marked areas” you see all boxes and can delete single ones again.
Open Redact PDF -
Decide what gets redrawn
Under “Redraw” the preset is “Marked pages only”. All other pages are taken over unchanged and stay searchable. Switch to “All pages” if nothing should be readable on the pages without marks either. For the resolution, 150 dpi is enough for pages that are read on screen. 300 dpi is print quality, but noticeably larger.
Back to Redact PDF -
Save and double-check
Tap “Redact and save”. The new file is named like your original with “-redacted” added, and the original stays untouched. Open it once and check every marked spot. Then try to select text there: nothing should happen. Finally, read the file with “PDF metadata”. There you see what else is stored in the document and can remove it.
Check PDF metadata
Why redrawing is safe
Every marked page is drawn as an image, and the black boxes are painted into that image. The image then replaces the page and the file is written completely fresh. The text, fonts and pictures of the old page are no longer part of it, so nothing can be recovered from underneath. The document properties of the original (title, author, creation date) are not carried over when the file is rewritten.
Good to know
- Redrawn pages are images. The text on them can no longer be selected, searched or read aloud. Links and form fields on those pages are lost, and the file usually gets larger. If it is too big for an email, Compress PDF helps.
- The tool does not know what is confidential. You decide which spots get redacted. Think of headers and footers, margin notes and names that appear on several pages.
- Password-protected PDFs cannot be opened. If you know the password, first create a copy without it using Remove PDF password.
- Photos and scans are already images. For a single photo there is Blur a photo.
- Redactions with legal effect (for example in official proceedings) can have their own requirements. If in doubt, ask the office that receives the file.