Soleil

Changing the main answer

An early concept put a countdown at the centre of the app: an estimate of the time until skin would start to burn, the feature the category treats as its headline. I researched that idea and proved my own hypothesis wrong. In practice, sunscreen often reduced the answer to a generic two-hour interval, while a more precise-looking figure without sunscreen risked suggesting that exposure was safe until the clock ran out.

So I went back to the UV reading and changed the hierarchy: the current UV index and its category are the first answer. The hourly shape of the day, a protection check and data freshness support that reading. During an outing, the clock records elapsed time, and sunscreen reapplication and protection checks are separate prompts. This was a product decision as much as a screen-design change: the interface should help someone act while being clear about its uncertainty.

Your Day and UV index: the current UV and its category answer first, the day’s shape supports it.

How the main answer changed: from a countdown to the current UV reading.

Designing for different days outdoors

Soleil has one core outing model for a walk, a school run, a holiday or an afternoon outside. Family profiles let someone see who is out, record sunscreen for each person and manage separate reminders. Adults who want more structure can add a guided Daily Glow routine to their own session; it’s optional, and it’s never a tanning flow for children.

The same thinking shaped the business model. The current UV reading, a basic protection check and an individual’s outing stay free; Pro adds household coordination, guided routines and deeper history. The essential safety information is never behind a paywall.

Left Choosing how today works, then time out and a protection check. Right A Sun timer or Daily Glow, with saved places for checking the UV somewhere else.

Testing beyond the phone screen

My family tested Soleil through TestFlight, including on a holiday when we were using it outdoors. That exposed a mismatch in the live session: after we recorded protection in the app, the Lock Screen activity could still say it hadn’t been recorded.

I traced the state across the outing and the Live Activity, then corrected the update path so the Lock Screen reflects protection recorded during a session immediately. That mismatch mattered because the most glanceable surface has to agree with the action someone has just taken.

Making the product feel like Soleil

The first interface was comparatively restrained, with light and dark screens and familiar system patterns. I explored several website directions before finding a more expressive visual language: warm colour, confident type, illustration and a sense of movement. I tried bringing that energy into the app through multiple selectable colour themes, then simplified it into one coherent palette and component system that works in light and dark appearances.

Left A Daily Glow routine and the Sun Journey milestones. Right Custom cards and charts: the routine editor and weekly sessions.

I curated a consistent set of AI-generated illustrations around the brand, giving the app recognisable people and moments. The finished interface uses custom cards, charts, controls and visual treatments across most surfaces, while keeping familiar navigation where it helps. Colour gives live conditions, actions, protection and history distinct roles, and the illustrations add warmth to a subject that can otherwise feel clinical. The website and the app became parts of the same visual world, and the same language later became the foundation for my iOS app Job Search, which I refined alongside Soleil.

Left Website hero: Know the UV. Enjoy the day. Right Website on mobile: hero and the UV answer.

Personalisation and scope

The competitor I studied estimated skin type from an AI photo scan without grounding it in the Fitzpatrick scale, the standard dermatologists use. Soleil’s onboarding lets people establish a Fitzpatrick skin profile through questions, a manual choice or an optional photo-assisted estimate they can confirm or change. I treated that profile as an input to cautious protection guidance, never a diagnosis or a guarantee of time in the sun.

Localised: Your Day in English, German and Japanese.

The Apple Watch companion shows UV and session time and can start an outing. With permission, Soleil reads Apple’s Watch-derived Time in Daylight and places those periods against the day’s UV curve, giving history more context without presenting daylight as an allowance. The product extends to widgets, Live Activities and the Dynamic Island, and its app and App Store material are localised into English, German, Spanish, French and Japanese. Just as deliberately, it doesn’t turn sunlight into a vitamin D number. The competitor tallied the vitamin D someone had made by sitting in the sun, a figure a phone can’t reliably measure and one that makes sun exposure sound like a goal, so I left it out.

Left Family profiles: skin types for each person, and the household’s outing record. Right Localised: Your Sun in French, Spanish, Japanese.