Jack Dorsey's new app tracks your sun exposure
Another day, another app from Jack Dorsey. The Twitter co-founder has announced an app called Sun Day just one week after releasing the peer-to-peer messaging app Bitchat.
While Bitchat is an internet-free app for communicating with friends over Bluetooth, Sun Day is all about, well, the sun. The latest app tracks your UV exposure and how much Vitamin D you get. It does this using a few personal details, including your location. Sun Day also asks you to share what kind of clothing you're wearing, such as "light (shorts & t-shirt)." There's an additional space for you to share your skin type, choosing from one of six options.
From there, it shows you the current UV index, high for the day, sunrise, sunset and burn limit — or the time you can be outside before your skin starts to burn. You can get your supposed vitamin D intake while outdoors by clicking "track UV exposure."
track your (vitamin) Da Sun Day app for Sunday.https://t.co/KKsq3LkLEj— jack (@jack) July 13, 2025
Like its week-old sibling, Sun Day is currently available in beta on TestFlight. You can download the service through Apple's App Store and see if there are spots available to try out Sun Day. This article originally appeared on Engadget at https://www.engadget.com/apps/jack-dorseys-new-app-tracks-your-sun-exposure-123306124.html?src=rss