Twitter Founder Introduces Sun Day, UV Tracking App And Vitamin D

Jack Dorsey created the Sun Day application (photo: X @jack)

JAKARTA Jack Dorsey, co-founder of Twitter, introduced the app he is developing. The man who also made Bluesky launch Sun Day, an app to track UV exposure.

In addition to tracking its beam exposure, this application is claimed to be able to detect vitamin D intake. Sun Day can be tried by developers via TestFlight on iOS. The source code can also be accessed via GitHub so that anyone can clone it.

In a post, Dorsey admitted that he did not use the Cursor, Claude Code, or Windsurf. He only uses an open-source coding tool calledANG.

When asked why Dorsey choseitude compared to Claude Code, the web developer said that 'Goose is an independent model'. There seems to be no other reason why Dorsey chose the coding tool.

The Sun Day application has a simple interface, where the application will display the UV Index for the user's location. The application will also display details such as cloud cover, when the sun is inundated, and when the sun sets.

Users can also choose their skin type from the six options provided and choose the type of clothing worn. With these two parameters, Sun Day will calculate the safe duration of sun exposure before the skin catches fire.

Sun Day can display the minimum required vitamin D intake. Users can start a UV exposure tracking session at any time. If the session is over, the app will display the amount of vitamin D obtained during the counting session.

Previously, Dorsey also showed a new application he developed to the public. The application is named saat. In his post, Dorsey said that the messaging application was designed to operate through the Bluetooth mesh network.

Users can send messages without requiring a mobile network or WiFi by using the application. Just like Sun Day, the saat application is also being tested on the TestFlight for iOS devices.