Any free APIs for checking if a domain name is taken?

[fuzzybabybunny]

I have an order form that I'm trying to create. One of the options is to order a custom domain name for a website, but I want to send an async request to an API to check if the domain name is available before the user submits the form.

I can't seem to find any free APIs that allow a simple domain availability check?

 

[mundane]

Couldn't you run a WHOIS system call to determine ownership/registration?

 

[fuzzybabybunny]

Couldn't you run a WHOIS system call to determine ownership/registration?

Uh, how do I run a WHOIS system call and have it return a JSON object which my code can understand?