SimplEOS doesn’t transmit anything else but the signed transactions to the blockchain, so your keys are safely encrypted only on your own computer at all times. All data is kept locally on your computer. We don’t have access to any of your information.
But please, as everything involving private keys, always do your own due diligence, SimplEOS doesn’t protect you if your computer is infected with some type of virus that records your screen or keylogs your keyboard.
Check out Dallas Rushing review about simplEOS wallet here