JPdfBookmark is described as 'S helps you create or edit bookmarks in PDF files, and set the selected bookmark to link to a website, open a file from the computer, or go to a specific position from the PDF file' and is a PDF Editor in the office & productivity category. There are five alternatives to JPdfBookmark for a variety of platforms, including Windows, Web-based, Mac, Android and iPhone apps. The best JPdfBookmark alternative is Adobe Acrobat DC. It's not free, so if you're looking for a free alternative, you could try KDAN PDF or Docs.Zone. Other great apps like JPdfBookmark are Ashampoo PDF Pro and VivPDF Editor.
Can't manually add bookmarks to existing pdf, and that's exactly what jpdfbokmarks does (and does that very well).