A single HTTP endpoint that tells you whether any domain is online. JSON responses, CORS enabled, works in any language or stack.
Live Demo
Type any domain and hit Check — the real API call happens in your browser.
API Reference
/api/check
Check whether a domain is up or down
| Name | Type | Required | Description |
|---|---|---|---|
domain |
string | required | Domain to check, e.g. github.com |
Both GET query-string and POST (JSON or form-encoded) are accepted.
| Field | Type | Description |
|---|---|---|
success | boolean | API call succeeded |
domain | string | Normalised domain checked |
status | string | up or down |
http_code | int|null | HTTP response code |
response_time_ms | int|null | Latency in milliseconds |
ip | string|null | Resolved IP of the domain |
checked_at | string | ISO 8601 timestamp |
error | string | Only present when status is down |
{
"success": true,
"domain": "google.com",
"status": "up",
"http_code": 200,
"response_time_ms": 187,
"ip": "142.250.80.46",
"checked_at": "2026-04-17T12:00:00+00:00"
}
{
"success": true,
"domain": "unreachable-example.xyz",
"status": "down",
"http_code": null,
"response_time_ms": null,
"ip": null,
"error": "Could not resolve host",
"checked_at": "2026-04-17T12:00:00+00:00"
}
60 requests per IP per hour. No API key needed. Limits reset automatically each window.
Call the API directly from browser JavaScript, SPAs, or any client-side code without a proxy.
We try HTTPS first, fall back to HTTP — so sites without a valid certificate are still checked.
| Code | Meaning |
|---|---|
| 200 | Check completed (the domain may still be down — read the status field) |
| 400 | Bad request — missing or invalid domain parameter |
| 429 | Too many requests — rate limit exceeded |
| 500 | Server error — something went wrong on our end |
Code Examples
Copy-paste ready snippets for every major language.
curl "https://isdownapi.com/api/check?domain=google.com"
Enterprise
IsDownAPI is free for individual developers and small projects. If you need higher rate limits, SLA guarantees, dedicated infrastructure, or a private deployment, get in touch.