Instant Username Search - Check out if your username is available

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

Handle Horse - Monitor when your desired Twitter handle becomes available

Handlescout - Get notified when a Twitter username becomes available

KnowEm - The Social Brand Search Engine; Find out if your brand, user, or product name is available on over 500 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.