When you create Your wallet you may provide a wallet password which will be used to encrypt You wallet data before send over network. We are not collecting Your wallet passwords and never transfer them over network, so You are only the person who knows the password and if You lost it there are no ways to recover your wallet.
On top of that we encrypt Your wallet with a master key on server side before save it to database. Therefore even if someone get access to Your database data it will be not possible to extract Your wallet data without master key (and without Your wallet password if you provide it).
Additionally we use HTTPS protocol to communicate with Gratzio server which adds another encryption level for transferred data.
We strongly recommend You to provide a wallet password and keep it secure.