# check-host.one

> Free global network checks: ICMP ping, TCP ping, HTTP, traceroute and DNS from measurement servers in 100+ countries, plus ASN/geolocation lookup. Use it to tell whether a host or site is down everywhere or only from some regions or networks.

No account or API key is needed. All interfaces share rate limits of about 20 checks per minute per client and 30 per minute against any one target.

## MCP server (recommended for AI agents)

- Endpoint: https://check-host.one/mcp (Streamable HTTP, stateless, no auth)
- Claude Code: `claude mcp add --transport http check-host https://check-host.one/mcp`
- Tools: `ping`, `tcp_ping`, `http_check`, `traceroute`, `dns_lookup`, `host_info`
- Every check tool takes `target` (hostname, IP or full URL), optional `locations` (free-form: country, city, continent, ASN or network name, e.g. ["Germany"], ["Tokyo", "AS13335"]) and `limit` (servers, 1-25). Results come back as a per-server summary plus a permanent result link.

## Links that run a check

Open https://check-host.one/?type=TYPE&target=HOST and the check starts on arrival. Results render with JavaScript.

- `type`: ping | tcp-ping | http | traceroute | dns | info
- `target`: hostname or IP
- `loc`: comma-separated ISO country codes, e.g. `loc=DE,US,JP`
- `limit`: number of servers, 1-25 (default 5)
- `port`: TCP ping, TCP traceroute and HTTP port
- HTTP: `method` (HEAD|GET|OPTIONS), `proto` (HTTP|HTTPS|HTTP2), `path`
- DNS: `dnsType` (A|AAAA|MX|TXT|NS|CNAME|SOA|PTR|ANY), `resolver`, `dnsProto` (UDP|TCP)

Example: https://check-host.one/?type=http&target=example.com&path=/health&loc=DE,US

## JSON API

- `POST /api/v1/measurements` with `{"type":"ping","target":"example.com","limit":5,"locations":[{"country":"DE"}],"measurementOptions":{"packets":3}}`. Returns `{"id": ...}`. Types: ping, http, traceroute, dns. For TCP ping use type ping with `"measurementOptions":{"protocol":"TCP","port":443}`.
- `GET /api/v1/measurements/{id}`: poll about once a second until `status` is not `in-progress`. A finished result carries `resultSlug`.
- `GET /api/v1/results/{slug}`: a saved result (kept 90 days), also viewable at https://check-host.one/r/{slug}
- `GET /api/v1/hostinfo?target=HOST`: ASN, organization and location
- `GET /api/v1/probes`: available measurement server locations
- Limits: at most 25 servers and 16 packets per measurement. Over-limit requests get 400; rate-limited ones get 429 with Retry-After.

## Reading results

- Ping: min/avg/max RTT and packet loss per server. 100% loss means the host did not answer from that server; loss from every server usually means the host is down or blocks ICMP (try tcp_ping).
- HTTP: status code and total time per server.
- Traceroute: hop list; where hops stop answering shows where the path breaks.

## Docs

- [OpenAPI spec](https://check-host.one/openapi.json) and [API catalog](https://check-host.one/.well-known/api-catalog)
- [auth.md](https://check-host.one/auth.md): no registration or credentials needed
- [Documentation](https://check-host.one/docs): tools, servers, permanent links, widgets, API, MCP, limits
- [Usage stats](https://check-host.one/stats)
- [Widget builder](https://check-host.one/embed/builder): embed a live check on another site