What are some alternatives?
When comparing Toby and Tabs Outliner, you can also consider the following products
Workona - A better way to work in the browser.
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 Buddy - Manage Your Browser Sessions
Raindrop.io - All your articles, photos, video & content from web & apps in one place.
Session Box - Using websites with multiple accounts at the same time is made easy.
Tree Style Tab - Tree Style Tab is an all-in-one Firefox extension that provides ability in order to operate tabs as a tree.