SunCalc org

Tldr: It's missing important features. The good: Simple and no ads. The bad: it doesn't show sunset and sunrise at the same time. It's missing the altitude arc, and it doesn't draw a line from the selected location to the sunset for some reason. Basically it's missing some very helpful features from the website and it's much less useful for photography because of that.

Superb idea and very well executed. Extremely useful for outdoor photography. I have just one quibble. When you set the time to a particular hour and you spend some time moving the map around, etc. after a few seconds the time switches to a random different hour which can be annoying.

Update: Recently reinstalled this app after uninstalled last year (due to annoying interface & various bugs). Now much better & really looking forward to exploring all capabilities. Now much nicer look, visual accuracy & easier to use. Like the map which distinct alternative to other similar apps & very interesting & useful. From the corresponding website this seems a reliable & trustworthy organisation & I'm glad the app is now matching the same high standards. Many thanks for the improvements.