Instant Username Search - Check out if your username is available

Handlescout - Get notified when a Twitter username becomes available

Namechk - See if your username is available on 100+ social networks

Startup name check - Startup Name Check is a free service allowing you to validate names for your next startup, side hustle or side-project. Works for numerous domains and social networks. All information is displayed in a clean table layout.

NameQL - Fast and friendly way to find a usable name for your idea, app or business

Shuuka - make it easy, use one nickname for all your networks