@dethveggie password managers should help support this feature. In addition to securely storing your passwords, they should keep track of who you were pretending to be at each particular site.
@jcornick@dethveggie after the LastPass breach, I'm worried about how those Notes fields are encrypted. #KeePassXC has custom attributes and you can add as many as you want. I've been using it for API keys and secret questions, but might as well go for broke and start making up entire identities.