What to look for in a UV app

A UV app can display an index and organize reminders. It does not measure damage to your skin or guarantee a risk-free amount of sun exposure.

Check the location, time and source

UV levels vary by place and time of day. The World Health Organization explains that a higher UV index means greater potential for skin and eye damage. Comfortable temperatures do not necessarily mean low UV exposure.

Check the displayed location, how recently the data was updated, its weather source and what happens when the network or UV data is unavailable.

Understand what a timer can do

A timer tracks elapsed time; it does not measure your skin’s actual response. Estimates based on skin profiles, UV or SPF have limitations. They should not be used to extend exposure.

What Tanly provides

Tanly is an iPhone and iPad app for checking the UV index and forecasts and tracking sun-exposure sessions. It includes a skin profile, duration estimates, a timer and SPF-related reminders. Downloading is free; some features require a subscription. No estimate guarantees risk-free sun exposure.

On iOS, Tanly uses WeatherKit and supports a manually selected place or permitted device location. The production code includes an unavailable state when UV data cannot be retrieved. Premium features and pricing are shown before purchase.

What an app cannot replace

Tanning exposes you to UV radiation and is never risk-free. Duration and SPF indications are estimates, not protection or medical advice. Do not extend sun exposure based on the timer. Notifications depend on device permissions, and UV information requires available weather data.

Use public-health sources for protection guidance and consult a professional when your circumstances require individual advice.

Sources consulted

• WHO — understanding the UV index.
• Tanly — official App Store listing and the supplied project source.