Online crossover- and box designers?

I'm tired of downloading software that seems like full of bugs and virus to my mainframe studio DAW computer, and rather use online tools which also allow me to sync my projects to phone, pad or whatever. I don't need much, just simple passive crossover schematics and bass reflex calculators. Anything out there?
 
Passive Crossover Designer and WinISD are used by many people. I dont think you have to worry about viruses. You can also look at Vituix CAD although ive never used it.

I don't think there are any online crossover calculators that will give you useful filters.