I am looking for a stable and secure way to log in services, sites whatever using spark or next.
I guess they are certain applications for phone and pc that can handle this.
Not sure what exactly you are looking for but if you haven’t done so (and assuming you have a spark) you should join the vivokey forum, There is some discussion about the vivokey API which can be used to provide identity to thrid party sites (assuming you are developing the site yourself)