Hi,
I develop the liskpaperwallet.com.
The entire source code is available here:
http://github.com/rferro/liskpaperwalletThe application is fully functional offline. You can download the source code and run offline in your browser and inspect in/out requests in dev tools.
No information is sent out.
And it is not a web wallet, more like a address generator for cold storage.
The algorithm is the same used in lisk core.