Jack Dorsey’s Latest App Tracks Sun Exposure
Jack Dorsey, the co-founder of Twitter, is diving into a series of app creations. After recently launching a Bluetooth-based messaging platform called Bitchat, Dorsey unveiled a new app this past weekend called Sun Day, aimed at helping users monitor their UV exposure and Vitamin D levels.
This innovative application is currently available through TestFlight for iOS users, with its source code accessible on GitHub for those interested in creating their own version.
Like many contemporaries in tech, Dorsey is embracing the vibe-coding trend. However, instead of opting for tools such as Cursor, Claude Code, or Windsurf, he is utilizing an open-source coding tool called Goose.
Sun Day is designed for ease of use, providing the UV Index for users’ current location alongside details like cloud coverage, sunrise, and sunset times. Users are able to choose their skin type from six different options and indicate their clothing. The app then calculates how long their skin can safely be in the sun before risking sunburn.
Moreover, the app offers insights into your necessary vitamin D intake. You can start tracking your UV exposure by tapping the “Track UV Exposure” button, and once the session is over, the app reveals the amount of vitamin D you’ve gathered during that time and throughout the day.
