Grumpy Old Geeks Products Sunday Product Sunday 3 mentions in 1 episode Sunday is Jack Dorsey’s app for tracking UV exposure and estimated vitamin D intake. Mentions 705: Vibe Defunding Jul 18, 2025 51:24 He has announced an app called Sunday. 51:42 This app tracks your UV exposures and how much vitamin D you get. 51:58 It shows the current UV index, high for the day, sunrise, sunset, and burn limit.