How to redact
- Add the PDF. The first page opens in the editor.
- Draw boxes. Drag over each name, number, address or passage to remove. Move between pages and repeat. Each box is listed; remove any you drew by mistake.
- Choose the resolution for redacted pages (150 dpi is usually right).
- Optionally rasterise the whole document, which removes hidden text, links and form data from every page, not just the ones with boxes.
- Redact and save. Download the result and check it.
Why most "redaction" fails
Redaction failures make the news regularly: court filings, government reports and company documents released with black boxes that anyone could remove. The cause is nearly always the same. A black rectangle was drawn on top of the text, but the text itself was still in the file. Select the area and copy, and the hidden words come out. Search the document, and they are found. Delete the rectangle in any editor, and they reappear. Highlighting text in black, or changing its colour to white, fails the same way.
Proper redaction removes the content. Professional software does that by editing the page's content stream, which is complex and easy to get wrong for unusual fonts and layouts. This tool takes the blunt, reliable route: every page with a box is rendered to an image, the boxes are painted onto the image, and the page is replaced by that image. Whatever was under the box no longer exists in any form in the saved file, and nor does any other text on that page.
What else is removed
- Selectable text on redacted pages. The whole page becomes an image. If people need to copy text from the rest of the page, redact as little as possible, or provide an unredacted version to those entitled to it.
- Document metadata. Title, author, subject, keywords and creation software are removed from the output, because they often contain names.
- Links, form fields and annotations on redacted pages.
Pages without boxes are copied unchanged, unless you tick Rasterise the whole document. Do that when hidden content elsewhere could matter: comments, form data, invisible text layers from OCR, or text hidden under images.
Checking your redaction
- Open the result and try to select text on a redacted page. There should be none.
- Search the document for a redacted word, such as a surname. It should not be found.
- Zoom in on the boxes and make sure nothing peeks out at the edges; each box is expanded by a pixel for that reason.
PDF Pro does this for you: it re-opens the output, confirms each redacted page has no extractable text, searches the whole file for any terms you list, and downloads a short report you can keep with the file.
Before you redact
- Know what must go. Names are obvious; signatures, account numbers, dates of birth, addresses in letterheads, file references, and faces in photos are easy to miss.
- Look at every page, including attachments merged in, and headers and footers.
- Keep the unredacted original somewhere secure. Redaction cannot be undone.
See also: how to redact a PDF properly and PDF metadata for stripping hidden properties without redacting.
On a tablet
Drawing redaction boxes works with a finger or stylus on a tablet. Zoom the page first for precision. On a small phone screen it is harder to cover text exactly; draw generous boxes, or use a larger screen for documents where precision matters.
Releasing a redacted document
Before you send or publish, open the redacted file fresh, not the one still open in your editor, and check it as a stranger would: try selecting text under the boxes, search for names, and look at the file's properties. Remember that the rest of each redacted page is now an image, so it will not be readable by screen readers. If accessibility matters, consider providing a separate accessible summary of the redacted pages.
Partial redaction of a page
If only one line on a page needs removing, that page still becomes an image. Its other text stays visible, just not selectable. To keep as much selectable text as possible, redact only the pages that need it and leave Rasterise the whole document unticked.
Draw boxes slightly larger than the text they cover; a margin of a millimetre or two costs nothing.
Privacy: the file stays on your device
Online PDF services upload your document to their servers, process it there and keep it for a while. This tool does the work in your browser. The file is read into the page's memory, processed by open-source libraries (pdf-lib for editing and pdf.js for rendering) in a background worker, and the result is offered back as a download. Nothing is sent anywhere, there is no account, and closing the tab discards everything. You can check it: open your browser's developer tools, watch the Network tab while you run the tool, and you will see no upload. After the page has loaded once it also works offline.