Seventeen free utilities for checking websites, URLs, ports, HTTP requests, IP addresses, domains, postcodes and more. Find problems faster, convert addresses, look up locations and understand what a network is doing.
Paste the HTML of a page and get a list of common accessibility problems: missing language, titles, alt text, link and button names, form labels, heading structure and iframe titles. It is a fast first pass, not a full audit.
Paste HTML
Results
Check whether a postal code matches the format used by a country. Choose the country, type the code, and see if it is valid. This checks the format only, not whether the address really exists.
Enter a postal / ZIP code and choose a country to see the city, state/district and coordinates. Data comes from the free Zippopotam service (GeoNames). Not every country or code is covered, and results are approximate.
Coverage varies by country. For some places only partial codes are available. Always verify important addresses with an official source.
Test many URLs at once. Each line is checked for valid syntax and then tested for a response. Browsers hide the exact status code of cross-site requests, so the tool reports whether a server answered and how long it took.
One URL per line (max 50)
Results
Collect every hyperlink from a block of HTML. Relative links are resolved against the base URL you enter, and each link is marked as internal, external, anchor or other. Export the list as CSV.
Paste HTML
Links found
Find out whether a port is open on a host. A browser cannot scan arbitrary TCP ports, so this tool does two things: it runs a web-port probe for ports like 80, 443 and 8080, and it gives you commands that test any port directly from your computer. Use the table to look up common ports.
Commands to test any port on your computer
Common ports
Check whether a website uses HTTP/2 or the newer HTTP/3. A browser can read the protocol of the page you are viewing, but not of other sites, so for any domain use the command below. The page check runs automatically.
Run this on your computer (Windows, macOS or Linux)
Protocol used to load this tool page
Protocol meanings: h2 is HTTP/2, h3 is HTTP/3 (QUIC), and http/1.1 is the older protocol.
Paste a raw HTTP request and check it against the basic rules: a valid request line, correct header format, a Host header for HTTP/1.1, and a Content-Length that matches the body.
Raw request
Checks
Traceroute shows each network hop between your device and a server, with the time each one takes. A browser cannot send these probes, so enter a target to get the right command, and use the guide below to read the output.
How to read the output
Convert an IPv4 address into the IPv6 forms used during the move to modern networks: IPv4-mapped, NAT64 and 6to4. You can also paste an IPv4-mapped IPv6 address to get the original IPv4 back. Note that an IPv4 address cannot become a real IPv6 address by itself; these are standard ways to represent or translate it.
Look up a domain name and see the IP addresses it points to. Queries go through Google's public DNS-over-HTTPS service, which works from the browser. Choose IPv4 (A records), IPv6 (AAAA records) or both.
Find website addresses inside any text, such as an email, a document or a list of links. Full URLs are reduced to their domain, and duplicates are removed. Optionally remove the www prefix.
Paste text
Domains found
Look up an IP address to see its approximate location, network owner (ISP or organisation) and time zone. The IP type (public, private, loopback and so on) is checked locally. Leave the box empty to look up your own public IP.
Location data is approximate and comes from a third-party service, which may limit how many lookups you can make in a short time.
Enter an IPv4 address and CIDR prefix (or a dotted netmask) to calculate the network address, broadcast, usable host range, total hosts and wildcard mask. Useful for planning LANs and understanding routing.
Ping measures round-trip time to a host. A browser cannot send ICMP packets, so enter a target and copy the ready-made commands for Windows, macOS or Linux.
High or increasing latency, or packet loss, can point to congestion or a problem on the path. Some hosts and firewalls block ping.
Look up the mail servers (MX records) for a domain. Results come from Google’s public DNS-over-HTTPS. Priority numbers show which server is preferred (lower number = higher priority).
A browser cannot freely inspect another site’s certificate chain. Enter a domain to get the OpenSSL and curl commands that show certificate subject, issuer, dates and protocol support.
Look for the “notAfter” date (expiry), the issuer, and whether the common name or SAN matches the domain you expect.
Paste a User-Agent string (or use the one from this browser) to see a simple breakdown of browser, OS and device hints. Useful when reading server logs or debugging client-specific issues.
MooneyCourses Networking Tools is a free set of utilities for developers, system administrators, students and website owners. Networking problems are often hard to see: a page does not load, a link is broken, a form is unusable for some visitors, or a domain points to the wrong server. These tools (accessibility, postcode validator & location finder, bulk URL, HREF extractor, port checker, HTTP/2, HTTP request, traceroute, IPv4/IPv6, domain to IP, domain extractor, IP search, subnet calculator, ping helper, MX lookup, SSL checker and user-agent parser) help you look at each part of the problem in a simple way. There is nothing to install and no account to create. Open the page, enter your input, and read the result.
Use the chips at the top to jump to any tool, or scroll through the list. Each tool has a short description, the input you need, and a results area. Some tools run entirely in your browser, so your data stays on your device. Others use a public service, and the description tells you which one. A few tools, such as the port checker and traceroute helper, need access to your network that a web page cannot have, so they provide the exact commands to run on your own computer.
Web browsers are designed to protect you. A website is not allowed to open arbitrary network connections, send raw network packets, or read the responses of other sites unless those sites explicitly allow it. This is why some checks are limited on a web page. We explain each limit clearly, so you know what the result means and what to run on your computer to confirm it.
Accessibility is about making a website usable for everyone, including people who use screen readers or keyboards. The checker reads your HTML and flags common problems: a missing language setting, a page without a title, images without alternative text, links and buttons with no name, form fields without labels, headings that skip levels, and iframes without titles. Fixing these issues often makes a site easier to use for everyone. Remember that automated checks cannot test colour contrast or real user experience, so also test with a keyboard and a screen reader.
Postal codes follow different formats in each country. Some are five digits, some mix letters and numbers, and some include a space or dash. The validator checks whether a code matches the expected pattern for the country you choose. It is useful for checkout forms, shipping tools and data imports. It cannot confirm that the address exists, so use a delivery address service for that.
When you maintain a large site or a list of resources, broken links appear over time. The bulk checker tests many URLs at once. It first checks the syntax, so a typo such as "htp" is caught immediately, and then sends a request to see whether a server responds. Because of browser security, the exact status code of a cross-site request cannot be read, so use the result as a fast reachability check and confirm important URLs with curl.
Links are the structure of the web. The HREF extractor collects every link from a block of HTML, resolves relative links against a base address, and labels each one as internal, external, anchor or other. This helps with SEO audits, link analysis, content inventories and research. Export the list to CSV to work with it in a spreadsheet.
A port is a numbered door on a server, and each service listens on a known port. Port 443 serves HTTPS, port 22 serves SSH and port 3306 serves MySQL. A port is "open" when a service accepts connections on it. Browsers cannot test arbitrary ports, so the tool runs a probe for web-style ports and gives you ready-made commands for Windows, macOS and Linux. The common ports table helps you identify what a number usually means.
HTTP/2 and HTTP/3 are newer versions of the web's transfer protocol. They are faster because they handle many requests over one connection, and HTTP/3 uses a modern transport that reduces delays on unstable networks. To check a site, run the command shown on this page. The tool also reports which protocol was used to load the page you are on, which is a quick way to see the difference.
Developers often debug APIs by reading raw requests. A small mistake, such as a space before a colon in a header or a Content-Length that does not match the body, can cause a request to fail in confusing ways. The request checker reads the request line, checks each header, confirms that HTTP/1.1 requests include a Host header, and compares the body size with the declared length.
When a connection is slow or fails, traceroute shows the path your data takes. Each hop is a router, and the timings help you locate where delay starts. Enter a target to get the correct command for your system. Remember that many routers do not answer probes, so a few asterisks in the middle of a route are usually harmless.
The internet is moving from IPv4 addresses, which have about four billion possibilities, to IPv6 addresses, which are much larger. During this transition, networks use special forms to represent IPv4 addresses inside IPv6. The converter shows the IPv4-mapped form, the NAT64 form used for translation, and the 6to4 prefix. It also reverses an IPv4-mapped IPv6 address back to IPv4.
Every domain name points to one or more IP addresses through DNS. This tool asks a public DNS service for the A record (IPv4) and AAAA record (IPv6) of a domain and shows the answers with their time-to-live values. Use it to confirm where a domain points after a server move, or to check whether IPv6 is configured.
Text such as emails, reports and chat logs often contains website addresses. The extractor finds domains and full URLs, reduces each one to its domain name, and removes duplicates. It is useful for building lists for research, cleaning up data, or checking which sites a document mentions.
An IP address can reveal approximate location, the organisation that owns the network, and the time zone. The search tool checks locally whether an address is public, private, loopback, link-local or multicast, then looks up the public details through a third-party service. Use it to investigate suspicious traffic or to understand where a visitor is connecting from. Location is approximate, usually at city level.
Enter a postal or ZIP code and a country to see the city, state or district, and map coordinates. The tool uses the free Zippopotam service. Coverage is good for many countries but not complete; always confirm important addresses with an official source.
Plan IP ranges by entering an address and CIDR prefix (or netmask). The calculator shows network address, broadcast, usable host range, total hosts and wildcard mask.
Ping and SSL tools give you the exact commands to run on your computer because browsers cannot send ICMP or freely inspect certificates. MX lookup uses public DNS to list mail servers for a domain. The User-Agent parser gives a quick read of browser, OS and device from a log string.
Start with the simplest check. If a page does not load, test the domain with the DNS tool, then the port with the command, and then the HTTP request. Keep sensitive information such as passwords and tokens out of request checks, and remove them before you share a result. When you run commands on your computer, read the output carefully, because a timeout can mean a firewall rather than a broken service.
Tools marked as running in your browser do not send your input anywhere. The DNS and IP lookups send only the domain or address you enter to the public service described on that tool. The tools work in current versions of Chrome, Edge, Firefox and Safari, on desktop and mobile.
Can this page scan every port on a server? No. Browsers do not allow arbitrary port scans. Use the commands provided on the port checker tool, and only test systems that you own or have permission to test.
Why does a bulk check show "reachable" but not the status code? Browsers hide the response details of cross-site requests for security. Reachability tells you a server answered. Use curl for the exact status.
Is the postcode validator accurate for every address? It checks format only. A valid format does not guarantee that the address exists.
Bookmark this page for quick checks whenever something on the network does not behave as expected. More tools and tutorials are shared on the MooneyCourses channel and website.