Check if a US business name is taken: state business registers, the .com and restricted words.
Free
One server, in sales & crm. Check if a US business name is taken: state business registers, the .com and restricted words.
Sales & CRM
Check if a US business name is taken: state business registers, the .com and restricted words.
The rest either hold an API key issued by the publisher or ask for nothing.
Listed without a verification tick. Read the listing before installing.