Drawing a black box over text hides it on screen and leaves it in the file, where it can still be selected, searched and copied. Redact here removes it: the page is rendered to an image with the marked areas painted out and written as a new page, so the content is not in the document at all. Find lets you redact every occurrence of a name or number in one go.
A rectangle sits on top of the content, which stays in the file. Redaction renders the page without it. After redacting, the text cannot be found by search, copied or recovered by removing a layer.
A redacted page becomes an image, so its remaining text is no longer selectable. Pages you do not redact are untouched.
No. Redaction happens in your browser, which is the point: a document that needs redacting is exactly the document you should not upload.
Yes. There are no paid tiers, no watermarks and no page limits. Downloading needs a free account with a confirmed email address, which is how the tool pays for itself: it introduces people to Eight Mile, the studio that built it.
Eight Mile PDF is free, built by Eight Mile, a studio that designs websites and builds web apps and SaaS products for businesses.