PDF metadata

Five fields are shown: title, author, subject, creator and producer. Two of them can be set, title and author, by typing a new value; leave a box blank and that field is left alone. There is also a strip option that clears all five plus the keywords list in one go.

Because you did not ask for a change. With strip off and both title and author blank, the tool only reports what it read and hands you nothing to download, since writing an identical copy would be pointless. Set a value or tick strip and a file appears with a -meta suffix.

Because it is read before anything is written. The text you see is the state of the document as it arrived, which is what you want when checking what a file was carrying. Open the downloaded -meta.pdf to see the new values.

No. The document is loaded with metadata updating switched off, so pdf-lib does not rewrite the producer or modification date behind your back when it saves. If you set only the title, only the title changes. That is the difference between an editor and a tool that quietly signs its own work.

No, and this is the important limit. Stripping clears the document information fields listed above. It does nothing to the page content, so names, addresses or draft text visible on a page are still there, and so is anything embedded in the file besides those fields. Treat this as tidying, not as sanitising.

Yes. Drop as many as you like and each is read separately, with its own report and its own output file. That makes stripping a batch before sharing them a single run. Nothing is uploaded: pdf-lib does all of it in a Web Worker in this tab.