About Redact
The most common mistake in redaction is to draw a black rectangle over a word. The rectangle hides it on screen and nothing else. The text is still in the file, and anyone can select, copy or search it. Documents have been released in exactly that state, with the confidential names recoverable by pressing Ctrl+A.
This tool removes the words from the page itself and places a black box where they were. Nothing remains underneath to select or copy, and the rest of the line stays as it was. After it has finished, the tool checks the finished file for the words you asked it to remove. It all happens in your browser, so the document you are redacting is not uploaded.
How to redact a PDF
- Choose the PDF. It should contain real text. If it is a scan, run OCR PDF first so that there is text to find.
- Type the words to remove into the box, separated by commas: for example "Acme Corporation, Alice Baker". Every occurrence in the document is found.
- Decide whether capitals matter. "Match capitals exactly" is off by default, so "ACME" and "Acme" both match.
- Press the button. The result line reports how many pieces were removed and on how many pages. Pages that could not be cleaned in place are turned into pictures to be sure, and the line says which.
- Check the preview, which shows the changed pages first and confirms that the words cannot be found in the finished file. Save the redacted copy.
When you would use it
- Removing names, addresses or account numbers before sharing a document.
- Preparing a document for disclosure with sensitive details taken out.
- Anonymising a case study, a report or a medical document.
- Hiding commercial figures from a version sent to a third party.
- Cleaning a document before it is published.
What it will not do
- It finds words you type. It does not detect sensitive information by itself, so you have to name what to remove, and spell variants separately.
- It works on text. A scan or an image of a name has no text to find, so run OCR first or use another method to cover it.
- Redaction cannot be reversed. The words are gone from the copy you save, so keep the original.
- Pages that cannot be redacted in place are made into pictures to be certain, which means their text is no longer text.
- It will not remove information that is elsewhere, such as in the file’s hidden properties. Use Remove metadata for those.
How it compares
Drawing a box with a markup tool, or covering text with a white shape, is cosmetic. Redaction proper deletes the content. The difference is the one that matters if the document leaves your hands.
Professional redaction features exist in expensive PDF suites and are well suited to large, regulated projects. For occasional use on a document or two, a tool that really deletes the text and then tests the result does the job.
We explain the problem more fully in is it safe to upload PDFs online, which includes the case for doing sensitive work in the browser.
Tips
- Include variants: "J. Smith", "John Smith" and "Smith" are three different searches.
- After saving, open the file, press Ctrl+F and search for one of the words. It should find nothing.
- Redact before you merge or number, and keep the unredacted original somewhere secure.