Jack Dorsey Launches Second Innovative App in a Week: A Game-Changer for Vitamin D Tracking on iPhone Users

Jack Dorsey, co-founder of Twitter and CEO of Square, has recently ventured into vibe-coding, resulting in the launch of several innovative applications within a seven-day span. The most recent addition to this series is Sun Day, an iPhone application currently available in beta testing through TestFlight, with no definitive release date announced or confirmation regarding its availability on Android platforms.

Sun Day serves as a personal UV exposure and Vitamin D tracking tool. Users initiate a session by pressing a button upon entering sunlight, and terminate it upon exiting, receiving an estimate of the Vitamin D gained during that period based on factors such as the local UV index, cloud cover, and sunrise/sunset times. It’s essential to remember that the app does not monitor the iPhone’s actual UV intake; instead, its accuracy depends on consistent button presses every time the user enters sunlight.

Sun Day also offers personalized settings, allowing users to specify their skin type among six options and choose their outfit for a more precise analysis of visible skin area. The app additionally provides burn alerts based on these factors, advising when shade may be necessary.

Last week, Dorsey unveiled Bitchat, a Bluetooth messaging application designed to facilitate communication in proximity without relying on traditional connectivity like cellular or Wi-Fi. According to Bitchat’s notes, the app utilizes Bluetooth Low Energy mesh networking for direct peer-to-peer messaging within physical proximity, with automatic message relay extending the effective range beyond direct Bluetooth connections.

Upon launch, Dorsey updated Bitchat’s GitHub page to note security concerns raised by several experts, stating, “This software has not received external security review and may contain vulnerabilities and does not necessarily meet its stated security goals. Do not use it for production use, and do not rely on its security whatsoever until it has been reviewed.”

Dorsey’s recent spree of app releases is attributed to an AI open-source platform named Goose, which assists users in transforming ideas into functioning applications quickly. Regarding Sun Day, Dorsey referred to it as a “weekend project,” implying potential continued innovation from him in the near future.