Spectacle
Spectacle – free and open source, simple software for creating screenshots from the KDE project for Linux
Shutter
Shutter – free and open source, multifunctional program for creating and editing screenshots
ScreenCloud
ScreenCloud – free anp open source, simple software for creating and sharing screenshots
Flameshot
Flameshot – free and open source, powerful yet simple screenshot creation software that lets you edit and upload screenshots
Ksnip
Ksnip – free and open source, cross-platform software for creating and editing screenshots
BleachBit
BleachBit – free and open source, multi-platform and powerful program for freeing up disk space and deleting confidential information
Ubuntu Cleaner
Ubuntu Cleaner – free and open source, simple program for cleaning the system of garbage and private information
Sweeper
Sweeper – helps to clean unwanted traces the user leaves on the system
Psensor
Psensor – free and open source graphical utility for temperature monitoring in Linux
Stacer
Stacer – free and open source optimization and monitoring tool for Linux system