Is there a way to find the days that constitute a weekend or workweek based on different cultures using the .NET framework? For example, some Muslim countries have a workwee
I won't give you a .NET answer, but I will say that you won't base it on "culture", but rather on country.
You can get country from IP with a fir degree of accuracy (but it will never be 100%). After that, I would suggest a lot of googling, because I doubt that you are going to find the code already written.
(you might also look into some open source calendar/appointment programs, especially widely-used ones, like on Linux, or maybe Lightning, the Thunderbird plug-in. If you wade through their code, you might find the data for this)
Fortunately, though, you just face a grind, rather than something difficult to implement.
Good luck!