This is a developer utility that lets you inspect the various system pasteboards. This can be useful to ensure your app is putting the correct data on NSPasteboard. The app refreshes the pasteboard contents live and can preview text, RTF, images, and anything that has a Quick Look preview.
Note that this is not a clipboard manager. If you're not a Mac developer, you probably don't want this app.
You can make the window always stay in front by enabling “Stay in Front” in the “Window” menu.
Use the up/down arrow keys to switch between the pasteboard items.
It hides obsolete system pasteboard types that have modern equivalents. This includes CorePasteboardFlavorType, NSStringPboardType, NSFilenamesPboardType, etc.
Tip: Right-click an item in the sidebar to copy the type identifier.
Requires macOS 11 or later.
Last macOS 10.15 compatible version.
It's a reference to the icon of Apple's old NSPasteboard sample app called Clipboard Viewer.
I don't have any immediate plans to localize the app.