Ksnip is a Qt based cross-platform screenshot tool that provides many annotation features for your screenshots.

Izici:

• Supports Linux (X11 and experimental KDE and Gnome Wayland support), Windows and MacOS.
• Taking screenshot of a custom rectangular area that can be drawn with mouse cursor.
• Taking screenshot of last selected rectangular area without selecting again.
• Taking screenshot of the screen/monitor where the mouse cursor is currently located.
• Taking screenshot of full screen, including all screens/monitors.
• Taking screenshot of window that currently has focus.
• Taking screenshot of window under mouse cursor.
• Take screenshot with or without mouse cursor.
• Capture mouse cursor as annotation item that can be moved and deleted.
• Customizable capture delay for all capture options.
• Upload screenshots directly to imgur.com in anonymous or user mode.
• Command line support, for taking screenshot and saving it to default location, filename and format.
• Customizable default location, filename and format for saving new screenshots with wildcards for Year ($Y), Month ($M), Day ($D) and Time ($T).
• Print screenshot or save is to pdf/ps.
• Annotate screenshots with pen, marker, rectangles, ellipses, texts and other tools.
• Add watermarks to captured images.
• Global HotKeys for taking Screenshots (Currently only for Windows and X11).
• Many configuration options.