◈ netchecks.org

17 checks · no account · self-hosted

Free Whois Lookup Tool

17 free network diagnostic tools in one dashboard.

FAQ

0 trackers · 14 languages · dark & light mode · self-hosted

My IP Check

Your public IP address and network location, detected automatically.

Loads automatically when you open NetChecks — no input needed. Use the Refresh button to re-check after switching networks or reconnecting your VPN.

Your browser

All-in-One Scan

Runs every relevant check against one IP or hostname in a single pass: DNS, whois, ping, traceroute, a well-known-ports scan (1-1024), HTTP headers and the SSL certificate.

Enter a domain or IP address and run it to check DNS, whois, ping, traceroute, common ports, HTTP headers, and the SSL certificate all at once.

Most checks run in parallel - typically finishes in about 30 seconds, longer if the target is slow or unreachable.

The port scan step only runs once the consent checkbox above is checked - every other check runs regardless.

Ping

Send ICMP echo requests to a host to check reachability and latency.

Enter a hostname or IP address and press Ping to send ICMP echo requests and measure round-trip latency.

You Host ICMP Echo Request (type 8) ICMP Echo Reply (type 0) measures: RTT · TTL · packet loss

      

Traceroute

Trace the network path (hop by hop) to a destination host.

Enter a hostname or IP address and run it to see every network hop between this server and the destination, with latency per hop.

You TTL=1 TTL=2 TTL=3 Host each hop replies "ICMP Time Exceeded" until TTL reaches the host

      

DNS Lookup (Nslookup)

Query DNS records: A, AAAA, MX, TXT, NS, CNAME, SOA, PTR, SRV, CAA.

Enter a domain, choose a record type (A, AAAA, MX, TXT, NS, CNAME, SOA, PTR, SRV, or CAA), then look it up.

You Root .com Auth NS ① query root ② referral → TLD ③ referral → auth NS ④ answer

      

Whois

Look up registration information for a domain or IP address.

Enter a domain or IP address to look up its registration details — registrar, owner organization, and important dates.

You Registry RDAP / :43 query: domain / IP reply: registrar, dates, name servers

      

Learn more about Whois

What it is

Whois queries the public registration database for a domain name or an IP address, revealing the registrar the domain was registered through, its creation, last-modified, and expiration dates, its current administrative status, and the name servers currently authoritative for the zone. For an IP address, the lookup instead reveals which organization the address block was formally allocated to.

How it works

Each TLD (.com, .fr, .org, and so on) is run by a separate registry that exposes its own queryable Whois service, and the response format can vary slightly from one registry to another. For IP addresses, it is the five regional internet registries (RIPE NCC for Europe, ARIN for North America, APNIC for Asia-Pacific, LACNIC for Latin America, AFRINIC for Africa) that each respond for their own geographic zone with the allocation information for the relevant address block.

Reading the results

The expiration date is by far the most consulted piece of information in an operational context - a domain that isn't renewed in time can cause a complete service outage, and sometimes a difficult one to fix quickly if a third party registers it in the meantime. Statuses such as clientTransferProhibited or clientDeleteLocked are perfectly normal protections deliberately set by the registrar against unauthorized transfers or deletions, and are not an anomaly to be corrected - if anything, their absence on a sensitive domain would be worth questioning. For an IP, the organization field reveals who actually operates the corresponding network, valuable for tracing a piece of traffic back to its source.

Common mistakes

A common confusion is reading the name servers (NS) shown in Whois as the domain's currently active DNS configuration, when it is really only the delegation declared at the registry level - the DNS zone actually being served by those servers can differ, and it is a direct DNS Lookup, not Whois, that gives the operational truth of the moment. Another trap: since GDPR came into force, many registrars now mask the domain holder's personal contact information by default in the public response - its absence is therefore not a sign of an anomaly or a badly registered domain, it has simply become the standard behavior.

When to use it

Proactively monitoring a client domain's expiration date, early enough to act before it lapses without a renewal already scheduled. Identifying the operator or hosting provider formally responsible for a suspicious IP address before sending them a properly documented abuse report. Verifying that a domain transfer between two registrars has actually completed successfully, by confirming the new registrar and the absence of any leftover lock status. Confirming which name servers are currently declared authoritative for a domain before starting a migration.

Blacklist Check

Check whether an IP address or domain is listed on public spam/abuse blocklists (DNSBL).

Enter an IPv4 address or domain and run it to check 7 public DNSBL/RBL blocklists at once - each shows as listed, not listed, or check failed.

You zen.spamhaus.org spamcop.net sorbs.net +4 more reverse-IP DNS query to each DNSBL zone, in parallel

      

TCP Port Scan

Check whether TCP ports are open on a host or IP: common ports, a custom list, or the full 1-65535 range.

Enter a host or IP, pick common ports, a custom list, or the full range, then scan to see which TCP ports respond.

You 22 open 443 open 3389 closed 8080 closed SYN → SYN-ACK = open · SYN → RST = closed

        
      

HTTP Header Inspector

Fetch the HTTP response status and headers for a URL.

Enter a URL to fetch its HTTP response status code and every response header the server sends back.

You Server GET / HTTP/1.1 200 OK + headers Content-Type · Strict-Transport-Security · X-Frame-Options …

      

SSL / TLS Certificate Checker

Inspect a host's TLS certificate: issuer, validity dates, and days remaining.

Enter a hostname to inspect its TLS certificate — issuer, validity dates, and days remaining before it expires.

You Host ClientHello → ← ServerHello + Certificate + Finished Root CA Intermediate Leaf (site) certificate chain of trust · validity dates checked

      

Geo-IP Lookup

Look up the geographic location and network info for an IP address. Leave empty to look up your own public IP.

Enter any IP address, or leave it empty to look up your own, to see its approximate location and network/ISP info.

IP address Geo / RIR database City · Country ASN · Org

Subnet / CIDR Calculator

Computed entirely in your browser — no data sent to the server.

Enter an IP address and CIDR prefix (e.g. 192.168.1.0/24) to instantly compute the network range, broadcast address, and usable host count.

network bits (prefix) host bits /24 example — split moves with your prefix

      

Speed Test

Basic download/upload throughput test against this server (accuracy depends on the server's own uplink).

Press Start to measure download and upload throughput against this server. Accuracy depends on this server's own connection.

You Server ↓ download ↑ upload throughput (Mbps)

      

Country Code Dictionary

ISO 3166-1 alpha-2 country codes — searched entirely in your browser.

Search or browse the list of ISO 3166-1 alpha-2 country codes, looked up entirely in your browser.

CountryISO Code

Phone Dialing Code Dictionary

International calling codes by country — searched entirely in your browser.

Search or browse international calling codes by country, looked up entirely in your browser.

CountryDial Code

World Clock

Pick a time zone to see the current time — drag the globe to spin it.

Pick a time zone from the list, or drag the globe, to see the current time there.

Your time
--:--:--
—

—

Selected time
--:--:--
—
— UTC±00:00
Difference vs. you —

—

Drag to rotate the globe.

French Mobile Network Status

Mobile antenna sites down or under maintenance in France, by operator (Orange, Free, SFR, Bouygues Telecom), from ARCEP's public data. Snapshot updated once a day by ARCEP - not a minute-by-minute feed.

Browse mobile antenna and fibre outage data by French operator — no input needed, updated automatically from ARCEP's public data.

Source: ARCEP, "Sites indisponibles" dataset, published under Licence Ouverte / Etalab 2.0 - commercial reuse explicitly allowed, unlike the IODA/CAIDA data this tab used before. The Normal/Watch/Alert badge is an in-house estimate (today's outage count vs. the median of prior days), not an official ARCEP classification. Source links below.

Most affected departments

Number of sites currently down or under maintenance, by department. Click an operator above to filter.

Data: Arcep — Sites indisponibles · Official network status map


Fixed Network (Fibre)

Fibre (FTTH) network quality by operator: reported-outage rate and connection-failure rate, from ARCEP's public data. Monthly indicators, 6-month rolling average - not a live feed like the mobile section.

Source: ARCEP, "Qualité des réseaux en fibre optique" dataset, published under Licence Ouverte / Etalab 2.0 - commercial reuse explicitly allowed. Source links below.

By operator (parent group)

Averages over the last 6 available months, per infrastructure-operator parent group.

Data: Arcep — Qualité des réseaux en fibre optique