Are my PDF files uploaded?

No. The document is opened and rewritten inside your browser. It is never sent to a server, and closing the tab discards it.

Is the redacted text really gone?

Yes. Pages with redactions are replaced by images in which the marked areas are solid black. The original text of those pages is not in the new file.

Those are the pages you redacted. Turning them into images is what guarantees the text is removed. Other pages keep their text.

Usually not: most editors only cover the text, which can still be copied out. That is the mistake this tool avoids.

JavaScript is turned off. InspireTools processes files in your browser, so the tools need JavaScript to run.

Black out text and areas of a PDF so they are removed for good, not just covered.