How this works in your browser
The distinction that makes this safe is what happens to a page you have marked. Rather than adding a black rectangle on top of the existing page, the tool renders that page to a canvas through PDF.js, paints the black boxes onto the canvas pixels, then embeds the finished canvas into a new document as an image via pdf-lib. The original text operators and vector graphics are never carried into the output, which is precisely why the hidden words cannot be recovered. Pages with no redactions take a different path entirely: they are copied across as-is, so they keep selectable text and full vector sharpness. That split is deliberate, since rasterising a whole document unnecessarily would cost quality and size for no security benefit.
Redact PDF vs. traditional online converters
| Feature | Redact PDF (in-browser) | Traditional online converters |
|---|---|---|
| File upload required | No - never leaves your device | Yes - file is sent to a server |
| Processing queue | None - starts instantly | Often, especially at peak times |
| Watermark on output | Never | Common on free plans |
| Usage limits | None - free, unlimited use | Often capped per day or file size |
| Works offline once loaded | Yes, for most tools | No - requires a live connection |
| Account required | No | Often, for anything beyond a trial |
How to use Redact PDF
- 1
Open the Redact PDF tool
Go to tools.slaytic.com and open the Redact PDF tool. No sign-up or account required.
- 2
Draw over what must be hidden
Page through the document and drag a black box over every piece of sensitive text, signature or image. Be generous at the edges rather than tight.
- 3
Save the redacted file
Apply the redactions and download the result. Redacted pages are written as flattened images with the content underneath already destroyed.
Common ways to use Redact PDF
Sharing documents under disclosure
Remove names, addresses or account numbers from a contract or record before it goes to a third party.
Preparing evidence or FOI responses
Black out third-party details in a document that has to be released, with the removal genuinely irreversible.
Publishing a redacted example
Turn a real invoice, report or form into a shareable sample with the identifying details destroyed rather than covered.
Frequently asked questions
Is the redaction truly permanent and irreversible?
Yes, on the pages you redact. Those pages are rasterised to an image with the black boxes already applied, so the original text and graphics beneath them no longer exist in the saved file. Nothing can be selected, copied or extracted from under a box because there is nothing there any more.
Do I need to flatten the PDF afterwards?
No. Redacted pages are already flattened to an image as part of the process, so there is no leftover text layer to clean up. Running the Flatten tool afterwards would change nothing about the redacted areas.
Can I redact text automatically by searching for a keyword?
The current tool uses manual drawing. Automatic text search and redact is not yet available - you draw over each area to redact.
What is the trade-off for this being permanent?
Pages you redact become images, so their text is no longer selectable or searchable and the file size for those pages usually grows. That is the direct cost of the content actually being destroyed. Pages without any redaction keep their text intact.
Does it remove metadata or hidden document properties?
No. This tool handles visible page content. Author names, revision history and similar document properties live elsewhere in the file and are not affected, so review those separately if the document is sensitive.
Is my document uploaded anywhere?
No. Rendering, redaction and re-saving all happen inside your browser tab, which is the point for a document sensitive enough to need redacting.