Regarding BlockChain.info u have stated this...
The developers of this wallet publish the source code. This means any developer in the world can audit the code. However, you still need to trust developers of this wallet when installing or updating the final software because it was not built deterministically like Bitcoin Core.
But, AFAIK, the complete source code is not open like Bitcoin-QT. Only the client side JS is open. Please check the bottom of
https://blockchain.info/wallet/securityWe dont know what is happening at the server side !!!