We don't support creating contact groups in our webapp yet. The reason is, that different vendors weren't able to come up with a standard for groups yet that works across platforms and devices. This will change, once all vendors move to the vCard 4.0 standard, but right now sadly all vendors use different methods to describe groups and none of them are compatible with each other.

That's why groups are not supported in the webapp currently. But if you have multiple devices that support groups, our backend system will of course sync them between your devices - you just won't be able to see them in the webapp.