Network & IP tools
Ping, traceroute, port checks, IP geo, ASN, reverse-IP, WHOIS, and subnetting.
Find the autonomous system, network owner, and prefixes behind any IP.
Domain age checkerFind a domain's registration date and how long it's been established.
IP geolocation lookupFind the country, city, ISP, ASN, and hostname behind any IP address.
My IPSee your public IP address and request details.
Ping testCheck whether a host or device responds to ICMP ping, and how fast.
Port checkerTest whether a TCP port (SMTP, POP3, FTP, …) is open on a host.
Port scannerCheck which common ports are open, closed, or filtered on a host.
Subnet calculatorNetwork, broadcast, mask, host range, and host count for any CIDR.
WHOIS / domain lookupRegistrar, registration & expiry dates, and nameservers for any domain.
When a server is unreachable or a service won't connect, you need to know whether the problem is the host, a port, or the network in between. These free network and IP tools let you ping and trace the route to any host, check which ports are open, and look up the geolocation, ASN, and ownership behind any address. Diagnose issues on demand, and let SJ Monitor's ping and port monitoring keep testing reachability so you hear about an outage before your users do.
Frequently asked questions
A host won't respond to ping — is it down?
Not necessarily; many servers block ICMP while still serving traffic, so also check the relevant port or HTTP status. The port and HTTP tools help confirm.
Can SJ Monitor watch a host or port continuously?
Yes. Ping and port monitoring check reachability on a schedule and alert you the instant a host or service stops responding.
When should I use traceroute instead of ping?
Use ping to confirm whether a host answers and how fast; reach for traceroute when it's slow or unreachable and you need to see which network hop introduces the delay or loss. Ping tells you "if," traceroute tells you "where."
Why are private and internal IPs blocked in these tools?
Allowing checks against addresses like 10.x, 192.168.x, or cloud metadata (169.254.169.254) would let the tools probe internal networks, a classic abuse vector. They're blocked by design; test those from inside your own network.
What's the difference between a port check and a port scan?
The port check tests one specific port you name; the port scanner probes a curated list of common ports at once to reveal your overall exposure. Use the first to verify a service, the second to audit what's open.
Other tool categories
Want any of this watched around the clock? Turn on SJ Monitor's ping & port monitoring — create a free account and we'll alert you the moment something changes.