Questions, answered plainly

It draws the shadow every mapped building is casting right now onto a live map, so you can see which terraces, benches, pitches and pavements are in the sun. You can move the map to any other moment to see where the sun will be later.

It combines the outline and height of the buildings around you with the position of the sun for that exact place and moment, and works out what each building blocks. The calculation runs on your phone.

Almost anywhere. Coverage is best in European cities and good in most large cities elsewhere. Where the building data for an area is thin, the app tells you so rather than quietly showing a map with nothing on it.

The sun position is computed to the same standard as professional sun-path tools. The uncertainty is in the building data rather than the arithmetic, and trees, awnings, fences and terrain are not part of it. Read it as where the sun can reach, not as a measurement of one particular chair.

The shadow map, the venues and their filters, today's sun timeline for any spot, the widget and sharing are free, along with three time jumps a day, the top five sunny spots nearby on iPhone or the first one on Android, and the sun hours report for today and midsummer. Pro removes those limits and adds saved places, sun alerts, the full year of sun hours, other days on the timeline, jumping to search results, the outdoor sports layers and the full weather sheet.

Partly. Building outlines are cached on your device for thirty days, so a street you have already looked at draws its shadows with no network at all. Somewhere new needs one request to fetch the buildings, and the weather needs a connection. Every calculation itself runs on the phone.

Yes. The Android app shares the solar and shadow calculations with the iPhone version. It has the same map, the same venues, the same sun hours and the same widget. The live countdown, the lock screen widget and invite codes are iPhone-only for now.

No. There is no account, no advertising identifier, and no analytics or crash reporting in either app. Your location is used to centre the map. The full detail is in the privacy policy.

The shadow answer is pure geometry and ignores weather entirely. The app does show live temperature, UV and a forecast alongside it, and a sun alert can stay quiet when the forecast says the sky will be covered.

Judging a place rather than a moment. It gives an address its hours of sun today, the longest unbroken stretch, and the same figures for midsummer, the equinox and midwinter, split into morning, midday and evening. People use it for house viewings, balconies and where to put a garden table.