How this works, and its limits
Your PDF is uploaded and converted with LibreOffice running headless, then streamed straight back as a download. Both the uploaded PDF and the converted document are deleted from the server as soon as that happens.
This works well for PDFs that were originally created from a document (reports, letters, exported Word files). It won't work on scanned pages or photographed text — recovering editable text from a scanned image needs OCR, which this tool doesn't do.