NovaWhy a black box on top isn't enough
Drawing a black rectangle over text in many ordinary PDF editors only adds a shape on top of the page — the original text is still sitting underneath it in the file, and can often be selected, copied, or recovered by anyone who knows to try. This has caused real, public data leaks: sensitive text "redacted" this way has been recovered from official documents more than once.
Genuine redaction has to remove the underlying content, not just cover it. That's a materially different operation from drawing a shape, and it's worth confirming any tool you use actually does it before trusting the result with something sensitive.
What actually gets removed
A page you mark for redaction gets converted into a flat image with the black boxes baked in, replacing the original text and vector content entirely — there's nothing left to select or extract from that page afterward, because the text objects themselves are gone, not just visually covered. Pages you don't mark are left completely untouched, keeping their original, still-searchable text.
Marking multiple areas or pages
A single page can have several redaction boxes — useful when more than one piece of sensitive information sits on the same page, like a name and an account number in different spots. Move between pages and add boxes to each one that needs it; a page with no boxes drawn on it is left exactly as it was.