I've seen many implementations of this exact thing, the basic ones are just sha1 or sha2(master + website domain) which generates a unique "password" for each s

I've seen many implementations of this exact thing, the basic ones are just sha1 or sha2(master + website domain) which generates a unique "password" for each site. This is just another implementation of the same idea. I've seen a few releases of simple scripts that do this for you as well, some work as bookmarklets, browser extensions, or single-page app websites. Visionary being a Python script I think makes it less portable, harder to use for average users, and definitely not mobile-device friendly.