How does blockchain.info api works? Calling 

https://blockchain.info/multiaddr?cors=true&amp;active=15PFsB56YYXwXSW6byaxHXfgGz2ySWnDzN


I get a json response which I can not figure out if it has some sort of error or that I'm mistaken.

The response show results in transaction 1206412 = 0.01206412BTC added to balance 0BTC should get 1206412 = 0.01206412BTC, however we get balance = 1201206412 = 12.01206412BTC, I think it's error in blockchain.info api or could you explain how the balance is calculated.
The issue was with how the transactions are sorted. The balance was being calculated with 9c8f1b918e6a6a2 being sorted before 46d529d722d1 (which is incorrect) despite them being ordered correctly in the json. Regardless it should be fixed now.