Something that does not exist for free, nor online anymore.
You can buy them or download them, but not use them like an online generator.
So the tool would create a calendar for planet X, with a Y rotational period and. Z orbital period around a sun. It would allow for multiple moos to zip around the planet and calculate their phases.
So planet Dinglebat has a rotational period of 43 hours and orbits it's sun every 467 days, it's moons all 4 have orbital periods of 4 days, 16 days, 56 days and 567 days respectively.
A week wpuld be a variable with Q number of days with Z number of weeks composing a month.
Could you wait, I know you can. Would you consider doing this.
Then later you can add vwather generator

I look forward to your reply.