Can this store different accounts for different sites?

I don’t know if all of the websites I use supports this security key. I’d like to use it to replace password managers, and have another key for two factor verification. Is it possible for the key to use different passwords and emails for logging into different sites?

I am not sure I understand the question here. If the site supports security keys (FIDO) you can use OnlyKey with that, if it supports TOTP you can use OnlyKey with that, if it does not support either you can use OnlyKey to store strong passwords for the site.

I guess what I’m asking is if the website is not properly setup with the right form types will this still work. Mostly worried about application and website compatibility.

What about local applications using Electron and such. In other words, does it support all popular web technologies so I don’t have to manually copy and paste?

You never have to manually copy and paste, OnlyKey types passwords, 2fa codes, etc.

Maybe this helps: