Overview

• Sun Day uses location-based data to display local UV index along with cloud cover, sunrise, and sunset times.
• Users choose from six skin types and clothing levels and manually toggle when they enter or exit sunlight.
• Based on user inputs, the app calculates safe exposure duration before burning and tracks daily vitamin D gains.
• This weekend’s release follows last week’s encrypted messaging app Bitchat, marking Dorsey’s second consecutive consumer app launch.
• Dorsey describes Sun Day as part of his ongoing public “vibe-coding” experiments and has hinted at more AI-assisted app releases.