Do you want to know what technologies (CMS, frameworks, platforms) are used on website?
Check out wappalyzer and its Chrome extension. Easy way to detect the environment used behind the website.
In Ubuntu/Linux, It is not so easy to draw flowchart and diagrams. Thanks to draw.io – free online diagram software for making flowcharts, UML, process & network diagrams..etc.
Very easy to use and highly recommended!
Password Checkup extension by Google: A must have Chrome extension to get alert if your username and password for wherever you sign-in is no longer safe due to appearing in a data breach. It helps you resecure accounts that were affected by data breaches.
Are you looking for MS Paint like application in Ubuntu/Linux?
Found a nice web-based classic MS Paint remake jspaint.app for drawing and editing images.
Hats off to creator of this!