What makes this site different is that your sensitive data is encrypted before it even leaves your browser.
The encryption software is downloaded into your browser and your data is encrypted with a pass phrase chosen by you.
That pass phrase never leaves your browser. You keep that to yourself. Your encrypted data is virtually uncrackable.

An implementation of the AES standard approved by the U.S. Government for Secret level of encryption.

AES (NIST FIPS-197) encryption.