The safest and most secure way to generate Bitcoin keys is on an offline computer or a hardware device that is a brand new install. However, when generating your Bitcoin wallet in our dashboard all key generation happens in your browser. Nothing touches our servers or any part of the internet. Once the keys are generated, only the Derivation Scheme and the Account Key Path are sent to us to create the BTCPay store, which can't spend funds. You can optionally backup your seed phrase by entering a password to encrypt the phrase to. When backing up a seed phrase, we encrypt the phrase to the password provided client-side then backup the encrypted data.