Redact PDF

How to use Redact PDF

1. Choose your PDF and use the page thumbnails or the page box to move between pages.
2. Drag on the page to draw a redaction box over each area to hide. Move, resize or delete boxes; on a phone, switch to Scroll mode to move the page.
3. Pick a mode. Secure mode flattens pages to images and is the default; choose a resolution and JPEG quality. Visual only mode just draws black boxes.
4. Press Apply, read the text-extraction check, then download the redacted PDF.

Why flattening is the safe way

PDF files keep content in layers: text, images and shapes. Covering a word with a shape adds a new layer on top without deleting the one beneath. Real-world leaks have come from exactly this mistake, where someone copied text from underneath a black bar.

Flattening fixes it because a rendered picture contains only pixels. Once the black rectangle is painted into those pixels, the covered content is gone from the picture, and the new PDF contains only the picture. The trade-off is that the whole document stops being searchable text.

Choosing resolution and quality

150 dpi is a good balance for reading on screen and sending by email. 100 dpi gives small files that are fine for large print. Choose 200 or 300 dpi if the pages will be printed or contain small type, remembering that file size grows quickly. Lower the JPEG quality for smaller files; very low values can make small text blurry.

• Draw boxes slightly larger than the text so no edge of a letter peeks out.
• Check every page, including headers, footers and page numbers that repeat the sensitive detail.
• Zoom the result and try to select text to confirm it behaves as expected.

What is and is not removed

In secure mode the output is a brand new PDF, so document metadata such as author and title, bookmarks, attachments, annotations and form data are dropped. If something sensitive is in the file name, change the name before sharing.

Visual only mode keeps the original file, with its hidden text, and adds black rectangles. Use it only for casual covering where the text itself is not secret. Everything happens in your browser with pdf.js and pdf-lib, so the document is never uploaded; very large or high-resolution documents may need a lower DPI if your device runs short of memory.

Why use this redact pdf tool

• Secure mode removes the real text. Each page is drawn to an image, the boxes are painted black on the pixels, and the image is saved into a new PDF. The original text layer is not carried over.
• Proof you can read. After redacting, the tool extracts text from the original and the result and reports how many characters were inside your boxes before and after.
• Honest visual-only option. A faster black-box mode is available, with a clear red warning that hidden text can still be copied from the file.
• Rotation and crop aware. Boxes line up with what you see even on rotated pages and pages with a crop box, and everything runs locally in your browser.

Frequently asked questions

More free tools