When comparing Kupfer vs CopyQ, the Slant community recommends CopyQ for most people. In the question“What are the best clipboard managers for UNIX-like systems?” CopyQ is ranked 2nd while Kupfer is ranked 5th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro It's the fastest
Pro Quick launch with a shortcut
You can activate the launcher with a shortcut and write into it.
Pro Simple to setup
Pro Easy to use
Pro Free
Pro Add notes or tags to items
Most effective with stacks that don't automatically delete the oldest members, tags and notes allow you to use CopyQ as a personal database for important information with easy access and retrieval.
Pro Cross-platform and cross-DE
CopyQ supports all major Linux desktop environments (including KDE Plasma, GNOME, Xfce, etc.), Windows and MacOS X 10.9+.
Pro Can sort and store based on content type
Built-in support for text, HTML, images or any other custom formats, allowing for type-based clip stacks that each have their own custom actions (open images in a photo editor, open URLs in a browser, etc.)
Pro Browse and filter items in history
Quickly locate that snippet you copied months ago but don't recall precisely what it was.
Cons
Con impossible to quit/start copyq via script
Con In linux, it sometimes does not react to shortcuts
Also buggy when hiding.
Con Sometimes copies filtered entries in between selection
Con Can't export images in bulk
Con Slow with many entries
Con Slow to place selected content on editor
Takes a while to place the selected text into the editor.