Owlead - Grow your Twitter with valuable followers, effortless
Hypegrowth - Hypegrowth is a personal Twitter assistant that allows to grow Twitter audience.
Fanbase - Fanbase helps enterprises grow a targeted audience of real people on Twitter.
Jooicer - Superpowers to boost your Twitter Growth
Swift Social - All-in-One Social Media Growth and Management Tool
Toolset.co - Twitter growth made easy, a bunch of tools to easily manage and grow your Twitter account.