Free online network tools
IP lookups, DNS tools, HTTP header inspection, port scanners, and network diagnostic utilities.
This is the one section of ToolChamp that cannot run inside your browser, and the page is explicit about it. A web page is not allowed to open a raw TCP connection, read a TLS handshake or query a WHOIS server on port 43, so these nine tools send the hostname, domain or IP you type to a small Cloudflare Function, which performs the lookup and returns the result as JSON. The functions hold no state between requests: every check is performed fresh, nothing is queued and no account is involved. What travels is exactly what you typed, and what comes back is what the tool displays. SSL Certificate Checker opens a TLS connection to port 443 and reports issuer, subject, validity dates, protocol version, cipher suite and key size; the A to F grade beside it is computed in your browser from those fields, penalising imminent expiry, TLS 1.0 or 1.1, weak ciphers such as RC4 or 3DES and keys under 2048 bits. WHOIS Lookup queries the registry's WHOIS server for the top-level domain and follows the registrar referral when the registry points at one, so you get the fuller record rather than the thin one. Domain Age Checker parses the registration date from the same source. Domain Availability Checker tries DNS first, because a name that resolves is certainly taken, then falls back to WHOIS or RDAP for the rest, and it checks a list of extensions in one pass. Port Checker attempts TCP connections to the ports you list, up to 100 per request in batches of 20, and reports open or closed with the common service name. Subdomain Finder reads Certificate Transparency logs through crt.sh, so it finds names that were issued a certificate rather than names that merely exist in DNS, and resolves the first fifty of them to show which still point at an address. IP Geolocation discovers your own address through ipify when you ask for it, then resolves any address through the free tier of ip-api.com and plots the country, region, city, coordinates, timezone and network operator. API Status Dashboard fetches the endpoints you configure and records status code and latency. Internet Speed Test streams filler bytes down from and up to the edge, timing the transfer and measuring latency with small probes.
9 tools · always free · no account needed
SSL Certificate Checker
Check SSL certificate details, expiry, and chain
WHOIS Lookup
Look up domain registration and ownership info
Port Checker
Test if ports are open on a host or IP
IP Geolocation
Find country, city, and ISP for any IP address
Subdomain Finder
Enumerate subdomains for a domain
Domain Age Checker
Check when a domain was first registered
Internet Speed Test
Test download speed, upload speed, ping, and jitter with a visual gauge
Domain Availability Checker
Check if a domain name is available across 30+ extensions instantly
API Status Dashboard
Quick health check for multiple API endpoints
How to choose the right tool
Certificate questions start with SSL Certificate Checker: it answers what expires when, which protocol and cipher were negotiated and whether the chain grades well before your monitoring catches it. Ownership and history questions belong to WHOIS Lookup, with Domain Age Checker when only the registration date matters, and Domain Availability Checker when you are naming something and need to sweep several extensions at once. Reachability is Port Checker's job — checking that 443 is open on a new host, or confirming a firewall change actually took effect from outside your own network, which is exactly the check you cannot make from inside it. Subdomain Finder is the reconnaissance tool: run it against your own domain before someone else does, because Certificate Transparency makes every certificate you have ever issued public, staging hosts included. IP Geolocation resolves an address from a log file into a country and network operator. API Status Dashboard watches a set of endpoints while you work, and Internet Speed Test measures the connection you are sitting on right now.
Frequently asked questions
Why do these tools send data to a server when the rest of the site does not?
Because browsers deliberately forbid what these checks require. JavaScript in a page cannot open a raw TCP socket, inspect a TLS handshake, or speak the WHOIS protocol on port 43, and cross-origin rules block most direct probing of other hosts. So the domain, host or IP you type is sent to a Cloudflare Function that performs the lookup on your behalf. Everywhere else on ToolChamp the work happens in your tab; here it genuinely cannot.
Can I check a device on my home or office network?
No. Every check that opens a connection — the certificate check, the port scan, the WHOIS and domain-age lookups — refuses hosts that are not publicly routable: private ranges such as 192.168.x.x and 10.x.x.x, loopback addresses and internal names are rejected before anything is attempted. That guard exists so the service cannot be used to probe internal infrastructure through us. For LAN diagnostics use a local tool on that network; these checks are for hosts reachable from the public internet.
Why does port 25 always come back closed?
Cloudflare blocks outbound connections on port 25 from its Workers platform, an anti-spam measure applied network-wide, and it also blocks connections to Cloudflare's own address ranges. A port in either group reports closed here regardless of what the target host is actually doing. That is the same observable result as a filtered port, so treat a closed result on 25 as no information rather than as evidence the mail server is down.
What does the speed test actually measure?
The throughput between your device and the nearest Cloudflare edge location. Download streams filler bytes from the edge, upload sends bytes to it, and latency comes from small timed probes. That is a good measure of your access line and local Wi-Fi, and a poor predictor of how fast a specific distant server will be. Run it more than once, on wired and wireless, before drawing conclusions, and remember other devices sharing the line affect the result.
Is the WHOIS and geolocation data live?
The WHOIS record is fetched live from the registry or registrar at the moment you ask, so it is as current as they publish. Geolocation is different: ip-api.com's free tier returns a database estimate, accurate to the country and network operator, roughly accurate to the city, and not accurate to a street address. Subdomain results come from Certificate Transparency logs, which can lag a freshly issued certificate by minutes to hours.
Are my lookups logged or rate limited?
The functions are stateless and keep nothing between requests, so there is no lookup history to browse or export. Upstream limits still apply and can surface as errors: ip-api.com's free tier allows about 45 lookups a minute across all users, crt.sh is often slow and is retried before giving up, and port scanning is capped at 100 ports per request. No account, key or payment is required for any of them.
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