f.lux - f. lux is a piece of software for Windows, Mac, Linux, iOS, and Android that provides a blue light filter over your screen. Research suggests limiting our exposure to blue light in the hours before bedtime can help us fall asleep faster.
Rainglow Color Themes - 320+ color themes for a variety of editors and software.
Mata - The night vision for the web. Read easier on the eyes.
Slack Themes - Make your Slack pretty with custom themes
f.lux for iOS - Auto adjust your iOS display based on the time of day
eM Client - eM Client is a fully-featured email client for Windows and macOS with a clean and easy-to-use interface. eM Client also offers features for calendars, tasks, contacts, notes, and chat.