Jack Dorsey’s Latest App: Track Your Sun Exposure!
Specifically, the Sun Day app tracks UV exposure in real time by drawing on data like the current UV index, cloud cover, and local sunrise/sunset times. Moreover, it personalizes advice: users enter their skin tone, clothing, and location, allowing the app to estimate safe sun durations and vitamin D synthesis. Notably, it’s currently in beta on TestFlight for iOS, and its open-source code is available on GitHub, enabling full transparency and community contributions.
How It Works
- Shows your local UV data, including cloud cover and UV intensity.
- Takes in skin tone and attire to adjust exposure thresholds.
- Tracks sun sessions manually tap start and stop to calculate your vitamin D gain and burn time TechCrunch.
- Plans future updates: blood-test integration, height/weight adjustments, and seasonal factors .
Tech Behind It
Notably, Dorsey developed Sun Day using Goose, Block’s AI coding assistant. This marks another entry in his so-called vibe coding weekend projects, following last week’s launch of his Bluetooth messaging app, Bitchat. According to reports, he codes over the weekend to explore ideas quickly prioritizing vibe and iteration over polished production and learning is the main goal behind these releases
Why It Matters
- Promotes safer sun habits by helping users balance vitamin D intake and skin protection.
- Fits the growing wellness-tech trend, merging personal health with AI-driven tools.
- Contributes to Dorsey’s creator journey, blending AI, open-source code, and tiny weekend-built apps like health tracking and decentralized messaging.

What Does the App Do?
Overall, the app helps users monitor their sunlight exposure conveniently. While details remain sparse, it appears that users can track their time in the sun, estimate vitamin D levels, or receive warnings about overexposure. As a result, this tool may empower smarter habits around sunlight and health.
Why Sun Exposure Tracking?
The focus on sun exposure is interesting, given the increasing awareness of both the benefits and risks associated with sunlight. Moderate sun exposure is vital for Vitamin D production, which plays a crucial role in bone health and immune function. However, excessive exposure can lead to sunburn, premature aging, and an increased risk of skin cancer.
Potential Implications
If Dorsey’s app is accurate and user-friendly, it could have several positive implications:
- Improved Vitamin D Levels: Helping users optimize their sun exposure to maintain healthy Vitamin D levels.
- Sunburn Prevention: Alerting users when they’ve been in the sun too long, potentially reducing the risk of sunburn.
- Skin Cancer Awareness: Raising awareness about the importance of sun safety and encouraging users to take protective measures.
The Details Are Still Emerging
Although no official press release has come from Dorsey or his team, the new Sun Day app is already stirring interest. Meanwhile, users are beginning to test it via TestFlight and share their early experiences across platforms. According to coverage from TechCrunch and The Verge, public details remain scarce. Nevertheless, as more testers provide feedback, additional information will likely surface. So, stay tuned for user perspectives and deeper insights as the rollout continues.