# Domain Availability API: Check Any Domain Free (2026)

Canonical HTML: https://domainsearchking.com/domain-availability-api

Availability: this text is an editorial snapshot, not a current registration guarantee. Use the [live domain checker](https://domainsearchking.com/verify) or [MCP](https://domainsearchking.com/mcp) before treating a name as available. Registry errors mean unknown, not available.

Developer guide

Updated November 1, 2026

No API key. No signup. No SDK to install. Two plain HTTP GET endpoints — one for a single domain, one for up to 120 at a time — both backed by live RDAP lookups against the authoritative registry.

## 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.

| Endpoint | Use case | Limit |
| --- | --- | --- |
| `/api/rdap?d=domain.com` | Check one domain | 1 domain per request |
| `/api/batch?d=a.com,b.com,...` | Check many at once | Up to 120 domains per request |

## 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.

**Building an AI agent instead of a script?** If you want domain checks wired into Claude, Cursor, or another AI agent via the Model Context Protocol — rather than calling the REST endpoints directly from your own code — use the [MCP server](https://domainsearchking.com/mcp) instead. Same underlying data, agent-native integration.

## 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.

### Try It Right Now

Paste a domain into the URL below and see the live response in your browser.

[Try /api/rdap →](https://domainsearchking.com/api/rdap?d=example.com) [See the MCP version](https://domainsearchking.com/mcp)

## Frequently Asked Questions

### Is there a free domain availability API?

Yes. Domain Search King's /api/rdap and /api/batch endpoints check live domain availability via RDAP with no API key or signup required, within a fair-use free tier.

### What's the difference between this API and the MCP server?

The REST API (/api/rdap, /api/batch) is for any programming language — plain HTTP GET requests returning JSON. The MCP server (/mcp) is specifically for wiring domain checks into AI agents like Claude or Cursor via the Model Context Protocol. Same underlying data, different integration method.

### Does the API use RDAP or WHOIS?

RDAP — the modern, structured, machine-readable replacement for WHOIS. It queries the authoritative registry directly and returns a definitive registered/available answer.

### How many domains can I check at once?

The batch endpoint accepts up to 120 comma-separated domains per request. For more, make multiple requests.

### Is the data cached or live?

Live. Both endpoints set Cache-Control: no-store and query the registry (via a caching proxy for speed, with a direct-registry fallback) at request time.

### Are there rate limits?

Yes, fair-use limits apply to keep the free tier fast for everyone. For high-volume or commercial use, contact Domain Search King about access.

### Prefer a Visual Search?

Describe your business and browse AI-generated .com names that are RDAP-verified available right now.

[Search on the homepage →](https://domainsearchking.com/) [Browse 290+ niches](https://domainsearchking.com/ideas)

## Related tools & guides

[Live search](https://domainsearchking.com/) [AI domain generator](https://domainsearchking.com/ai-domain-name-generator) [AI business names](https://domainsearchking.com/ai-business-name-generator) [AI agency names](https://domainsearchking.com/ai-agency-name-generator) [Shopify names](https://domainsearchking.com/shopify-name-generator) [Namelix alternative](https://domainsearchking.com/namelix-alternative) [AI taken rescue](https://domainsearchking.com/ai-suggested-domain-taken) [Domain taken?](https://domainsearchking.com/domain-taken) [Verify a domain](https://domainsearchking.com/verify) [Hallucination index](https://domainsearchking.com/ai-hallucination-index) [Catchy ideas](https://domainsearchking.com/catchy-domain-name-ideas) [One-word .coms](https://domainsearchking.com/available-one-word-domains) [How to choose](https://domainsearchking.com/how-to-choose-a-domain-name) [How to check taken](https://domainsearchking.com/how-to-check-if-a-domain-name-is-taken) [MCP for agents](https://domainsearchking.com/mcp) [Niche ideas](https://domainsearchking.com/ideas) [Features](https://domainsearchking.com/features) [About](https://domainsearchking.com/about)