Okular isn’t as advanced as something like PDF Studio but it covers all the basic PDF editing functions.
It’s the default PDF app for a number of Linux desktop environments for it is reliable. Okular is another popular name in the Linux space when it comes to PDF Editors. Inkscape is available for all three major desktop operating systems: Windows, macOS, and Linux.
It isn’t the most advanced PDF editor out there but it can get the job done if all you want is to edit text or images on a PDF. What you might not like is that the interface is more like Adobe Photoshop or GIMP because it is ultimately a photo editor first. Some of the PDF editing features in Inkscape are not even available on some other dedicated PDF editors unless you pay for the full or Plus version. Inkscape is quite a popular name when it comes to viewing or editing pictures but it is also a serious PDF editor.
