Is my private password data stored on your systems?

Your encrypted data is stored on our systems, yes, but the plain, readable version is never, ever, sent to our systems.

It is encrypted in the web browser first using your private password (or rather, a unique hard-to-guess key related to your password), then sent to our servers. So we get a pile of encrypted data and we store it. You ask for it back and then you decrypt it in the browser.

Without the key, the data is useless. Key stays in your browser alone, and is deleted after 5 minutes in the browser. You can delete it sooner by just refreshing the password home page.