Determing if an internet domain name is already registered is not a trivial task. You cannot simply make a DNS lookup, as a registered domain name might not have a DNS record. The most reliable way to do so, is by doing a Whois lookup. If you want to know if the domain is free, you have to:
The Whois API will handle this for you with these endpoints:
||Checks if a domain is available or already registered. The result includes also the whois server response.|
||Queries an arbitrary whois server|
We maintain a comprehensive whois server list. If you don't want to use our API you can of course use this list for free, as we've published it as open source. This whois server list gets updated frequently. It contains more than 800 top level domains and more than further 300 second level domains. The Whois API supports them all.
It's for free! Our basic plan comes for free. It includes 11000 requests per month.