Redacting a PDF means removing sensitive text so it cannot be recovered — not just hiding it behind a black rectangle. This distinction matters more than most people realize. A shape drawn on top of text in many editors leaves the underlying words fully intact in the file, ready to be copied, searched, or lifted out with a few clicks. Real redaction destroys the data underneath. This guide explains how to do it properly, and how to do it in your browser without uploading anything.
The most common redaction mistake
The classic failure looks convincing on screen: someone draws a black box over a name or a Social Security number, saves the PDF, and sends it out. But in the file, that box and the text are separate layers. Anyone can select the text beneath the box, copy it, and paste it somewhere readable. Some viewers even reveal it if you change the box color. High-profile leaks have happened exactly this way — court filings and government documents released with "redactions" that were undone in seconds.
The lesson: covering is not removing. To be safe, the text itself has to be gone from the file, not merely obscured.
How proper redaction actually works
There are two reliable methods.
The first is content-aware redaction, offered by paid desktop software like Adobe Acrobat Pro. It finds the actual text objects under your marks and deletes them, then paints black over the area. The upside is that the rest of the page stays as real, searchable text.
The second method is flattening. Each page is converted into a plain image with the black areas painted directly into the pixels, then rebuilt as a PDF. Because the page is now a picture, there is no separate text layer left anywhere — nothing survives beneath the boxes to be recovered. The trade-off is that the whole page becomes an image, so text on it is no longer selectable or searchable.
Redacting text with the Redact PDF tool
The free Redact PDF tool on Every Boring Tool uses the flattening method, and it runs entirely in your browser. Your file is never uploaded to a server, there is no sign-up, and there is no watermark on the result. That matters for redaction specifically: the whole point is to handle sensitive material, so a tool that keeps the file on your own machine is a better fit than one that sends it away.
Here is how to use it:
- Open the tool and choose your PDF. It renders every page on screen so you can see exactly what you are working with.
- Drag a box across any text you want to hide — a name, an account number, an address. Drag again to add more boxes. You can overlap several boxes to cover an awkward shape.
- Use "Undo last box" or "Clear this page" if you place one wrong. On a multi-page document, use the Prev and Next buttons to move between pages; boxes are tracked per page and a counter shows your total.
- When every sensitive area is covered, click "Apply & build redacted PDF." Each page is flattened to an image with the black boxes baked in.
- Click "Download redacted PDF" to save the result.
Because the output is a flattened image of each page, the text under your boxes is genuinely discarded — not layered over. That is what makes it safe to share.
An honest caveat: cover everything, and check first
Flattening only removes what your boxes actually cover. If a name appears three times on a page and you box two of them, the third is still there in full. The tool cannot find text for you — you decide what gets covered, so read each page carefully before you finish. Watch for the same detail repeating in headers, footers, tables, and margins.
Also remember what flattening does to the rest of the page: after redaction, none of the text is selectable or searchable anymore, because the page is now an image. For a document you just need to share safely, that is usually fine. If you need the surviving text to stay searchable, this is not the right approach — content-aware redaction in desktop software is.
When a different approach is better
- Very large or scanned documents. Rendering every page in the browser is fine for typical files, but a document with hundreds of high-resolution pages can be slow or memory-heavy. Split it first, or use desktop software.
- You need the rest of the page searchable. Flattening removes the text layer entirely. If searchability matters, use a tool that does content-aware redaction.
- Encrypted or password-protected PDFs. These usually cannot be read directly. Open the file in a viewer, use Print → Save as PDF to make an unprotected copy, then redact that.
- Metadata and hidden data. Redaction covers what is visible on the page. It does not touch document metadata, attachments, or comments. If those could contain sensitive information, clear them separately.
The bottom line
Good redaction is about removing data, not decorating over it. Draw your boxes carefully, cover every instance of anything sensitive, and confirm the method you use actually destroys the underlying text rather than hiding it. For a quick, private, in-browser job, flattening with the Redact PDF tool does exactly that — just double-check every page before you hit download, because the tool covers only what you tell it to.