How to Black Out Text in a PDF (Real Redaction, Not a Highlighter)
Need to hide names, addresses or numbers in a PDF before sending it? Do it properly — the right way removes the text underneath, not just covers it.
You need to share a document, but parts of it are sensitive — a witness name, an account number, a social security number, an address. You want to hide those parts so the rest of the document is still useful.
This is harder than it looks, and a lot of people get it wrong. Here's how to do it right.
The mistake almost everyone makes
The wrong way: open the PDF in a generic editor, draw a black rectangle over the text you want to hide, save the file.
This does not actually hide the text. The original characters are still in the PDF underneath the rectangle. Anyone who:
- selects the area with their mouse,
- copies it (Cmd-C / Ctrl-C),
- pastes it into Notes / Word / Notepad,
...gets the original text. The black box was visual decoration only.
Real cases where this went wrong:
- 2020 court filings in a high-profile US case — sensitive names recovered by anyone with a PDF reader.
- 2018 corporate due-diligence reports — competitor names recovered from a leaked PDF.
- Multiple government documents — redacted personal info recovered by journalists.
Don't be that organisation. Real redaction removes the underlying text, not just covers it.
How real redaction works (and how to do it on pdfty)
When you use a proper redaction tool:
- You mark the areas to hide.
- The tool deletes the text content in those regions before saving the PDF.
- A solid black bar is drawn on top in place of the deleted text — partly to make it visually obvious, partly so the page layout doesn't shift.
- The exported PDF has no recoverable trace of the original text.
Step-by-step:
Open the redact tool
Go to pdfty.com/tools/redact. Pro feature — $9/mo. Free trial available.
Upload the PDF
Drag in your document. Upload is HTTPS-encrypted. The file lives on our server only as long as you're working on it.
Draw boxes over the text to hide
Click and drag a rectangle over each name, number or block you want gone. You can also use Find & Redact — type the term (e.g. a name) and every instance gets highlighted automatically.
Click Apply Redactions
This is the moment the text actually gets deleted. Until you click Apply, the marks are just preview — easy to undo. After Apply, the text is gone for good.
Download — verify the redaction worked
Open the file. Try to select the redacted areas with your mouse and copy. You should get nothing (or just empty space). That's how you know it's real.
What you should usually redact
| Information | Why hide it | Common scenarios |
|---|---|---|
| Full names of third parties | Privacy regulations (GDPR, HIPAA, CCPA) | Court filings, witness statements, HR records |
| Account numbers | Identity theft / fraud | Bank statements shared for tax / loan / dispute purposes |
| Social security / national ID | Direct identity theft risk | Anything you send a recruiter, landlord, or service provider |
| Home addresses | Stalking / doxxing risk | Court documents, news materials, public filings |
| Dates of birth | Combined with other data = identity theft | Medical records, school transcripts |
| Internal pricing / margins | Commercial sensitivity | Contracts you're sharing with a third party |
| Signatures | Forgery risk | Templates / examples shared publicly |
How to verify the redaction worked
Three quick checks every time:
- Try to select the black bars with your mouse. In a properly redacted PDF, you can't — there's nothing to select. If you can highlight and copy text, the redaction failed.
- Search for the redacted term. Hit Cmd-F / Ctrl-F in your PDF reader and type the redacted name or number. It should not find any matches.
- Check the file in a plain text reader. Open the PDF in a text editor and look for the redacted text. Real redaction leaves no trace.
Frequently asked questions
Can I unredact a file later?
No — that's the point. Once Apply Redactions is clicked and the file is exported, the original text is gone. Keep a backup of the original somewhere safe if you might need it later.
What if I redact the wrong thing?
Until you click Apply Redactions, all marks are just preview overlays — you can drag, resize or delete them freely. After Apply, the only way to "fix" a mistake is to redact more or start again from the original. Apply only when you're sure.
Does this work for scanned PDFs (images of paper)?
Yes, but with a caveat. Scanned PDFs have no selectable text — the "words" are just pixels. Drawing redaction boxes over them paints over the pixels, which does hide the text (because there's no text data underneath to recover). Just be careful about resolution: if you redact on a low-res scan, double-check the bars actually cover the words at full zoom.
For best results, run a scan through our OCR tool first — that adds a real text layer, which lets you use Find & Redact to catch every instance of a name in seconds.
What about metadata? Names hidden in author / creator fields?
Good question. PDF files have hidden metadata (author, original filename, software used). Our redact tool also strips metadata by default during Apply. So author names and editing history are gone too.
Why is redact a Pro feature?
Because the legal stakes of getting it wrong are huge. We invest extra care: proper deletion of text content (not just visual covering), metadata stripping, batch Find & Redact, an audit log of what was redacted, and a verification step that confirms the export is clean. Pro is $9/mo with unlimited redactions — that's lunch money to avoid a privacy incident.
Can I do this offline?
Adobe Acrobat Pro has a redact tool that's similar in approach — but it's $20/mo for a subscription you might not otherwise need. Free PDF editors (Mac Preview, Foxit Reader free) do not have real redaction — they only let you draw a rectangle, which is the wrong way (see "the mistake everyone makes" above).
What's the file size limit?
20 MB on the trial. Pro removes that limit.
Is the original ever sent to anyone?
No. Upload over HTTPS, redaction happens on our server, you download the redacted version. Both files (original and redacted) are deleted within 1 hour. For top-secret material — court-sealed documents, classified — we recommend desktop software, since the file never leaves your machine at all.
The pdfty team builds privacy-first online PDF tools — compress, convert, OCR, sign and protect. Files are deleted within 1 hour. About us →
