host.tools

Domain WHOIS

Domain /api/v1/domain/whois

Registrar, dates, name servers, contacts, DNSSEC status.

Try: host.com checkhost.com crypt.tools marketcap.to tokencalculator.com
Related: DNS lookup (dig) DNS propagation Domain WHOIS SSL certificate inspector HTTP headers Security headers grader MX lookup SPF tester DMARC tester
j4n.cz REG-INTERNET-CZ
Registrar
REG-INTERNET-CZ
Created
03.12.2018 01:44:48
Age (days)
2714
Server
whois.nic.cz
Name servers
  • ns1.no-ip.com
  • ns2.no-ip.com
  • ns3.no-ip.com
  • ns4.no-ip.com
Raw WHOIS response 
%  (c) 2006-2021 CZ.NIC, z.s.p.o.
% 
% Intended use of supplied data and information
% 
% Data contained in the domain name register, as well as information
% supplied through public information services of CZ.NIC association,
% are appointed only for purposes connected with Internet network
% administration and operation, or for the purpose of legal or other
% similar proceedings, in process as regards a matter connected
% particularly with holding and using a concrete domain name.
% 
% Full text available at:
% http://www.nic.cz/page/306/intended-use-of-supplied-data-and-information/
% 
% See also a search service at http://www.nic.cz/whois/
% 
% 
% Whoisd Server Version: 3.15.0
% Timestamp: Sat May 09 07:04:46 2026

domain:       j4n.cz
registrant:   CZJAN
nsset:        J4NCZ
registrar:    REG-INTERNET-CZ
registered:   22.05.2025 23:19:04
changed:      22.05.2025 23:44:23
expire:       22.05.2029

contact:      CZJAN
name:         Jan Maňásek
registrar:    REG-MOJEID
created:      03.12.2018 01:44:48
changed:      03.12.2018 01:58:08

nsset:        J4NCZ
nserver:      ns1.no-ip.com 
nserver:      ns2.no-ip.com 
nserver:      ns3.no-ip.com 
nserver:      ns4.no-ip.com 
tech-c:       CZJAN
registrar:    REG-INTERNET-CZ
created:      22.05.2025 23:44:21
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Bulk lookups · monitors · webhooks · 10,000 API calls/day

Upgrade to Pro for $19/mo. Cancel anytime. Works with the same API you already use.
How to use Domain WHOIS
  1. 1
    Paste your input

    Enter the value at the top — domain, IP, URL, email, ASN, hash, whatever fits this tool. The smart input auto-detects type.

  2. 2
    Click "Inspect"

    host.tools issues real probes (DNS, HTTP, TCP, TLS, WHOIS where applicable) and renders the result in milliseconds.

  3. 3
    Open the API tab

    Every web tool has a sibling /api/v1/domain/whois JSON endpoint with the same payload. One copy-as-curl click and you're scripting it.

Why this matters

WHOIS, expiry, DNSSEC, name servers — domain metadata is the single most-overlooked outage source. Lock it down before someone else does.

API equivalent
/api/v1/domain/whois?q=j4n.cz 
curl -s '/api/v1/domain/whois?q=j4n.cz'
Embed this tool
<iframe src="/domain/whois?q={INPUT}&embed=1"
  width="100%" height="600" frameborder="0"></iframe>

Drop into any HTML page. The embed=1 flag hides nav and footer.

FAQ · Domain WHOIS

Common questions

Is Domain WHOIS free?
Yes — every tool is free on the web with a 200/hour rate limit per IP. The matching API endpoint /api/v1/domain/whois is free up to 100 requests/hour, no key required.
Where does the data come from?
Real-time probes against authoritative sources (DNS root, RIRs, registries, the target server itself), plus partner data feeds from hostinfo.com (GeoIP/ASN) and hostcheck.com (reputation).
How fresh are the results?
Live by default. Cached for 5 minutes to make repeat queries instant; pass ?nocache=1 for a forced refresh.
Can I run this from the command line?
Yes — every tool ships with a copy-as-curl. There's also an official CLI: host.tools domain whois YOUR_INPUT.
Can I monitor results over time?
Pro tier lets you schedule any tool to run every 1/5/15/60 min and alert on diff. See monitors.
host.tools Pro

Run Domain WHOIS on a schedule. Get pinged when it changes.

Pro gets you bulk lookups, monitors, webhook alerts, history, exports and 10,000 API calls/day. $19/mo.

See pricing Tour monitors
  • ✓Schedule any tool — every 1, 5, 15, 60 min
  • ✓Diff against last run, alert on change
  • ✓Webhook + email + Slack + PagerDuty + OpsGenie
  • ✓Bulk CSV upload, 1,000 inputs per job
  • ✓Export results as CSV / NDJSON / Excel
  • ✓90-day history, comparison view