it is server-side app, not client-side
Let me explain what this means in an easier way than all posts above me do already:
SCAM!
SCAM!
SCAM!
SCAM!
SCAM!
SCAM!
There are only 2 sites I trust for paper walletshttps://www.bitaddress.orghttps://bitcoinpaperwallet.com/(of course you'll have to download these and use them offline as instructed on those sites to be safe from spyware)