You need to share a PDF, but first you want to black out a name, an address, or an account number. So you draw a black box over it in a PDF editor and call it done.
Here’s the catch: the text under that black box can often still be copied and pasted. This guide explains why, and shows you how to redact a PDF so the hidden text is truly gone, using the free PDF Redaction Tool.
It looks blacked out, but the text is still there. Not many people know about this trap, so I built a tool that makes “I thought I hid it” mistakes impossible.
What is redaction?
Redaction means blacking out the parts of a document that shouldn’t be seen. It’s standard practice for government records, legal filings, and any document that contains personal information.
On paper, a black marker does the job. PDFs are different. A PDF page contains text data for searching and copying, separate from what you see on screen. Drawing a black shape on top doesn’t remove that text underneath. Select the blacked-out area and copy it, or open the file in another app, and the hidden words can come right back.
To redact properly, you have to remove the underlying text itself, not just cover it up.
What this tool does
- Lets you cover any part of a PDF by dragging over it with a mouse or finger (in black, gray, or white)
- Leaves no text data under the redacted areas
- Handles multiple pages and multiple areas at once
- Works entirely in your browser — your PDF is never uploaded
Here’s how it works: each page is turned into an image, your redactions are painted onto that image, and a new PDF is built from the images alone. Every page becomes a single flat picture, so there’s no text left to copy.
How to use it
Step 1. Open the tool and select your PDF
Open the PDF Redaction Tool and choose the PDF you want to redact. All of its pages appear as images.
On Windows, if the tool says the file couldn’t be loaded, the downloaded file may be blocked by a security flag. Right-click the file, open Properties, check Unblock on the General tab, and select it again.
Step 2. Drag over what you want to hide
Drag from the top-left to the bottom-right of the area you want to hide, and it gets filled in. You can redact as many areas as you like, on as many pages as you need.
Tip: make the box a little bigger than the text so no edges of letters peek out. If you make a mistake, click that page’s Reset button to start the page over.
You can choose Black (default), Gray, or White as the fill color. Black is the norm for documents going outside your organization, since it makes clear that something was removed. Gray works well for internal documents, and white makes the area look blank, like correction tape. Whichever you pick, the text underneath is removed the same way.
Make each box a little larger than the text
Step 3. Save the redacted PDF
When you’re done, click Redact & save PDF. A new PDF with your redactions is saved with _redacted added to the file name. Your original PDF is not changed.
Step 4. Check that it worked
Open the saved PDF and try to select and copy the blacked-out area. If nothing gets selected, and nothing pastes, it worked. Searching for a hidden name with your PDF viewer’s search box is another reliable check.
That one quick check before sending prevents almost every “they could still read it” accident. Until it becomes second nature, I’d recommend doing it every time.
When this comes in handy
- Sending a copy of an ID: hide numbers and details that the recipient doesn’t need
- Sharing quotes or invoices: remove client names or pricing before sending a document to a third party
- Using real documents as examples: hide customer and staff names for training materials or blog posts
- Posting documents online: remove addresses, phone numbers, and email addresses before uploading
FAQ
Why does the black box in my PDF editor sometimes leave the text behind?
Most PDF editors have a “draw shape” feature and a separate “redact” feature. A black rectangle drawn as a shape leaves the text underneath intact. The dedicated redaction feature does remove the text, but the difference isn’t obvious, and it’s easy to reach for the shape tool by mistake.
If my PDF is a scan, is drawing a box over it safe?
A plain scan has no text data, so there’s nothing to copy. But if text recognition (OCR) was applied when it was scanned, there may be invisible text hidden behind the image. You can’t tell by looking, so it’s safest to use a method that removes the underlying text either way.
What about hiding part of a photo or screenshot?
For image files, use Pixelate or Blur Part of an Image. Keep in mind that light pixelation or blur can sometimes let people guess the text from its shape. For numbers and names, a solid fill is safer than a blur.
Things to watch out for
- No text on the page can be selected afterward: because every page becomes an image, you can’t search or copy text anywhere in the saved PDF. Keep the original if you need selectable text
- The file may get larger: converting pages to images can make the PDF bigger than the original. If it’s too large to email, you can break it up with PDF Split
- Check the file name, too: a file named something like “John_Smith_resume.pdf” gives away the very thing you hid. Rename the saved file if needed
- Password-protected PDFs can’t be opened: remove the password first
Summary
Covering text in a PDF isn’t enough — you have to remove the text data underneath. This tool turns each page into an image before redacting, so there’s no hidden text left to copy.
After saving, try selecting and copying the redacted area to make sure it’s really gone before you send the file.
