SynthTime

The best light of the day is short. The blue hour often lasts only 15–20 minutes, and many apps guess it as "sunset plus 45 minutes", which is wrong in most places for most of the year. SynthTime calculates it from the sun's real altitude: blue hour is the time the sun is 4° to 6° below the horizon, golden hour the time it is between 4° below and 6° above.

Pick a place with one tap (browser location), a quick city or typed coordinates, choose a date and time zone, and SynthTime lists the morning and evening blue hour, golden hour, sunrise and sunset, each with a start and end time. A timeline bar shows the whole day's light, and live chips count down to the next window.

Turn the compass dial, or use your phone's compass, toward the direction you want to shoot. For each window SynthTime tells you where the sun is and whether your subject gets front, side or back light. It has no account, no ads and no tracking, and makes no server calls — your location is used only inside your browser.