Clear (not to be confused with Clean). The application with the most minimalistic design you can think of. And this is a plus, because it does not weigh the head. I don’t know how to describe it succinctly, except as a "task scheduler with and without reminders." The tasks there are hammered into the list. The most important are placed above, the less important - below. The list is a color gradient (in the original version - from bright red to yellow). Paid.
CCleaner. Cleans browser cache and more. Free, but cleans as well as paid counterparts.
Giphy Capture. Makes GIFs. Free.
Encrypto. Encrypts selected folders and files, you can set any password. Free.
Depends on what you are doing. For all, I can definitely recommend flux. This small application changes the color temperature of the screen (for example, gives it a warm, yellowish tint) when it gets dark and dark. This allows your eyes to fatigue less, and you will also get better sleep - "normal" white light interferes with the rhythm of sleep / wakefulness in the body.