Multiple cryptocurrencies
Prefer private key and address generated client side
support multiple cryptocurrencies
nothing too fancy
I don't really understand, do you want to buy or sell a webwallet source ?
Because if you want to buy, it is useless as there is a lot of open source web wallets on github, supporting several cryptos, and some have a built-in API.
I don't care if you use opensource. Actually open source is better, but I do need a web developer as well.