Online Wallet base Source for a new AltCoin

[Chien]

Hello, I'm looking to make a new AltCoin, just to understand better how this world works. Here on bitcointalk there are many guides about creating new altcoin from example litecoin source code, and that's fine. But what I'm unable to find is a good open source base to manage an online wallet for a potentially new altcoin.

I mean I would like to deep understand the way of how manage a basic online Blockchain, private keys of the users and so on. So is there something that could help me in this project?

Thank you!