Fetch Balance of wallet without Core wallets of all coin? I'm creating an exchange like service, I need some for showing all transaction to user like deposit and withdrawal but I'm not using core wallets of any coin, using paper wallets for wallet creation and I want to show balance of user and transaction. So, is there any API available for so that I can fetch such details of user? Please give such API for Altcoins also or provide me name of any wallet through which my task can be completed.
You can check the balance of an address even if it is not a core wallet by using block explorers. Here are two useful ones for checking the balance of a Bitcoin address:

https://blockchain.info/api/blockchain_api

and an Ethereum account:

https://etherscan.io/apis#accounts

You may wonder how it is possible to check the balance of an 'offline' paper wallet. It comes down to how Bitcoin (and other Bitcoin-like blockchains) work. At the most basic level, you have a private key. You can generate a public key from the private key and then an address from the public key. Bitcoins are sent to this address. 

Blockchain explorers can check the balance of any address, even addresses that have not been generated yet! This is because an address is simply a string of letters and numbers that conform to a particular format. 

You can read more about addresses here:

https://en.bitcoin.it/wiki/Address