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Redact a PDF: remove the passage, not just hide it

Choose a file, mark the passages, save. The result holds no characters where you marked — and the tool reads the finished file back and tells you what it found.

Choose a file

Drop a PDF or an image here The file stays on your device. Nothing is uploaded.

Why a black rectangle is not enough

Drawing a black rectangle over an account number in a PDF viewer only covers it. The text sits unchanged in the file and can be selected, copied, searched for, or shown by another program.

The PDF standard says so plainly: applying a redaction shall remove all traces of the content, and clipping or image masks shall not be used for it (ISO 32000-1, clause 12.5.6.23).

What this tool does instead

Every page is redrawn, the marked areas are painted into that image, and a new file is built from the images. The result contains no text characters, no embedded fonts, no form fields, no annotations, no layers, no attachments and no earlier revisions — not because they were stripped, but because they are never created.

A PDF comes back as a PDF and a picture as a picture. You get the same kind of file you put in, without the part that had to go.

The National Archives and the Information Commissioner's Office recommend exactly this: the information has to leave the bit stream, not merely the displayable record.

What it costs

A redacted PDF cannot be searched, nothing can be copied out of it, and a screen reader finds no text. That is the price of there being nothing else left in it either.

Keep the original. The redacted version is for handing on, not a replacement.

The check after saving

Once written, the finished file is opened again and read back. If a single character comes out, the file is reported rather than saved.

Searching the file for the string would be no substitute: text in a PDF is compressed, and even decompressed many producers split a word across separate pieces. The search then finds nothing while the text extracts perfectly well.

Images

A JPEG or PNG goes through the same path and comes back as a PNG. Two things disappear that most people never think about: the small preview inside the EXIF data, which often still shows the uncropped original, and extra images some cameras append behind the actual photograph.

The check here is a different one: the finished file is taken apart and read for anything besides its pixels — including after the end marker, where some programs leave remains.

The EXIF orientation is applied first, so a portrait photograph does not come out on its side.