Tree Style Tab - Tree Style Tab is an all-in-one Firefox extension that provides ability in order to operate tabs as a tree.

App Cloner - Clone your Android apps so you can use multiple logins.

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.

Dual Space - It is a first application that is compatible with WhatsApp completely.

Firefox Multi-account Containers - Sign in to two different accounts on the same site

island - a free and opensource alternative to parellel space