Domain Availability API: Check Any Domain's Status With One HTTP Request

Two Endpoints, No Setup

Most "free" domain APIs require a signup, an API key, and a rate-limit dashboard before you can make your first call. This one doesn't. Both endpoints are plain HTTP GET requests that return JSON — paste the URL into a browser and you'll see the response.

Single Domain: /api/rdap

curl "https://domainsearchking.com/api/rdap?d=example.com"

→ {"domain":"example.com","available":false}

available is true, false, or null if the check couldn't be completed. There is no separate "check availability" step to remember — the response IS the current registry state, queried at request time.

Batch: /api/batch

curl "https://domainsearchking.com/api/batch?d=example.com,anotherexample.com,thisnamelikelyavailable.com"

→ {
  "results": {
    "example.com": false,
    "anotherexample.com": false,
    "thisnamelikelyavailable.com": true
  },
  "n": 3,
  "via": "c2-cache"
}

Pass up to 120 comma-separated domains in one request. The via field tells you which path answered the query (a caching proxy for speed, or a direct registry fallback if the proxy is unreachable) — useful for debugging, not something you need to branch on.

Code Examples

JavaScript (fetch)

const r = await fetch("https://domainsearchking.com/api/rdap?d=example.com");
const { domain, available } = await r.json();
console.log(domain, available ? "available" : "taken");

Python (requests)

import requests
r = requests.get("https://domainsearchking.com/api/rdap", params={"d": "example.com"})
data = r.json()
print(data["domain"], "available" if data["available"] else "taken")

Batch check in Python

import requests
domains = ["example.com", "anotherexample.com", "mycoolstartup.com"]
r = requests.get("https://domainsearchking.com/api/batch", params={"d": ",".join(domains)})
for domain, available in r.json()["results"].items():
    print(domain, "available" if available else "taken")

Why RDAP Instead of WHOIS?

RDAP (Registration Data Access Protocol) is the structured, machine-readable successor to WHOIS. WHOIS returns free-text output whose format varies by registrar, which means you end up writing fragile regex to parse it. RDAP returns clean JSON directly from the authoritative registry, purpose-built for programmatic use. This API queries RDAP under the hood so you never have to parse WHOIS text yourself.

Rate Limits and Fair Use

Both endpoints are free with generous fair-use limits — no API key required for normal use. If you're building something high-volume or commercial, reach out about dedicated access rather than working around the limits; it keeps the free tier fast for everyone else.

Frequently Asked Questions