What are some alternatives?
When comparing MySessions and Multiloginapp, you can also consider the following products
OneTab - Whenever you find yourself with too many tabs, click the OneTab icon to convert all of your tabs into a list. When you need to access the tabs again, you can either restore them individually or all at once.
Session Box - Using websites with multiple accounts at the same time is made easy.
Tabs Outliner - Next Generation Session, Windows, Tabs Manager and a TooManyTabs Solution That Really Works.
Firefox Multi-account Containers - Sign in to two different accounts on the same site
Multifox - Multifox is an extension that allows Firefox to connect to websites using different user names.
Tree Style Tab - Tree Style Tab is an all-in-one Firefox extension that provides ability in order to operate tabs as a tree.