About Redact PDF
Redact PDF permanently removes sensitive information — it doesn't just cover it with a black box. Search for specific words or switch on auto-detectors for emails, phone numbers and credit-card numbers, and every match is blacked out. To make the hidden text genuinely unrecoverable, each page is flattened to an image, so the words underneath are gone for good. Nothing is uploaded; the whole process runs on your device.
- No uploads
- Browser-only
- Works offline
- 100% free
How it works
- 1
Load the PDF and choose what to hide
Drop one PDF, then toggle detectors (emails, phones, cards) and/or type exact words or numbers to search for. Matching is case-insensitive.
- 2
Redact
SnapToolz reads every page with on-device OCR, blacks out each match, and rasterises the pages so the covered text can't be copied back out.
- 3
Download the redacted file
The output is a flattened PDF with the sensitive content genuinely gone. Review it, then download or share.
Redaction versus the fake black box everyone reaches for
The single most common data leak in shared PDFs is a ‘redaction’ that only hides the text visually. A black rectangle drawn in a PDF viewer, or highlighter set to black, sits as a separate object on top of the words — delete it, or just copy-and-paste through it, and the secret is back. True redaction removes the underlying text so there is nothing to recover.
| Method | Text underneath | Safe for secrets? |
|---|---|---|
| Black rectangle drawn over text | Still in the file, selectable | No — movable, deletable, copyable |
| Black highlighter over text | Still in the file | No — the text pastes straight out |
| Changing font colour to black | Fully intact | No — invisible on screen, plain in the source |
| Redact PDF (this tool) | Gone — page flattened to an image | Yes — nothing left to recover |
Flattening to an image is why the output is no longer selectable or searchable — that loss of the text layer is exactly what makes the redaction permanent. Run [OCR PDF](/pdf/ocr/) afterwards only if you need it searchable again.
A redaction checklist before you send
- Turn on every relevant auto-detector (emails, phones, cards) and add exact search terms for names, account numbers and addresses the detectors won't know.
- Remember OCR is capped at 30 pages — for a longer file, split it and redact each part, then heed the tool's warning about skipped pages.
- Open the redacted output and try to select text over the black bars; on a correctly flattened page you'll get nothing.
- Redaction removes visible text but not document metadata — strip the title, author and timestamps with Edit PDF Metadata before sharing.
- For the full pre-share routine across file types, see the guide on cleaning files before sharing.
Frequently asked questions about Redact PDF
How is this different from drawing a black rectangle over text?
A black box drawn in most editors sits on top of the text — anyone can move it, delete it, or copy the words underneath. This tool rasterises each page to an image after blacking out matches, so there is no text layer left to recover. The redaction is permanent, which is the whole point.
Why is the output no longer selectable or searchable?
That's the security trade-off, by design. Flattening pages to images is what makes the hidden text unrecoverable — but it also means the whole page becomes a picture, so the output PDF isn't selectable, isn't searchable, and may be larger. If you need it searchable again, run OCR PDF on the redacted file.
Is there a page limit on the auto-detection?
OCR is capped at 30 pages because reading every page is slow, especially on a phone. Pages beyond the cap pass through unchanged rather than being silently trusted as clean — the tool warns you, so split a long document and redact the sections separately.
Should I trust the auto-detectors to catch everything?
Treat them as a strong first pass, not a guarantee. The email, phone and card detectors catch common formats, and text search catches exactly what you type — but an unusual number format or a misspelled name can slip through. Always review the redacted output before you send it.
Privacy, offline use, browser support, and pricing questions are answered on the site-wide FAQ.