A growing collection of browser-based networking tools for IT professionals, system administrators, and developers. No installs, no signups — just open and use.
Tools
LiveWhat Is My IP Address?
Instantly find your public IPv4 address with geolocation details including city, region, country, and ISP.
→IP Geolocation Lookup
Look up the geographic location, ISP, and ASN for any public IP address. See what sites see when you connect.
→MAC Address Vendor Lookup
Enter any MAC address to identify the hardware manufacturer using the IEEE OUI database.
→WHOIS Lookup
Query domain and IP registration details via modern RDAP — registrar, expiry dates, name servers, and abuse contacts.
DNS Record Checker
Query A, AAAA, MX, TXT, CNAME, and NS records for any domain using Google DNS-over-HTTPS.
→MX Record Lookup
Check the mail server records for any domain, with priority values and a deliverability verdict.
→SPF Record Lookup
Fetch and parse the SPF TXT record for any domain with a running count against the 10-lookup limit.
→TXT Record Lookup
Retrieve all TXT records for any domain — SPF, DMARC, DKIM, domain verification strings, and more.
→SPF, DKIM & DMARC Checker
Verify all three email authentication records for any domain in one click — SPF, DKIM, and DMARC together.
→MTA-STS and TLS-RPT Checker
Check a domain’s MTA-STS TXT record, policy file, and TLS-RPT record in one pass — validated against RFC 8461 and RFC 8460.
→SPF & DMARC Generator
Build a correctly formatted SPF or DMARC TXT record from guided options — ready to paste into your DNS.
→Reverse DNS Lookup
Find the hostname (PTR record) associated with any IPv4 address via in-addr.arpa resolution.
DNS Propagation Checker
See how a DNS change has spread across resolvers in different regions. Useful after updating any record.
→DNS Speed Test
Benchmark response times across popular public DNS resolvers from your current location to find the fastest one.
IPv4 Subnet Calculator
Calculate network address, broadcast address, usable host range, and subnet mask from any IP and CIDR prefix.
→CIDR to IP Range Converter
Expand any IPv4 CIDR block to its first and last IP, network, broadcast, and total host count.
→IP Address ↔ Binary Converter
Convert between dotted-decimal, binary, hexadecimal, and integer IP formats with class and scope detection.
→IPv4 to IPv6 Converter
Convert any IPv4 address to IPv6 — IPv4-mapped, 6to4 prefix, expanded hex, and per-octet notation.
→Subnet Mask Cheat Sheet
Every CIDR prefix from /0 to /32 with subnet mask, wildcard mask, and host counts in one filterable table.
SSL Certificate Checker
Check the SSL/TLS certificate for any domain — issuer, expiry date, days remaining, and Subject Alternative Names.
→DNS Blacklist Check
Check whether an IP address or domain appears on common DNS-based block lists used by mail servers and firewalls.
→Common Port Number Reference
Searchable database of 75+ well-known TCP and UDP port numbers with service names and descriptions.
Bandwidth Transfer Calculator
Estimate file transfer time at any network speed — supports MB/GB/TB and Mbps/Gbps with bits-vs-bytes conversion.
→AI Crawler Checker
Check which AI crawlers your robots.txt allows or blocks and see your llms.txt configuration if present.
→Networking Glossary
Search 200+ networking terms with plain-English definitions, A–Z jump navigation, and links to the right tool or guide for each.
IP Addresses
LiveHow to Find Your Public IP Address
What your public IP reveals, why it matters, and the fastest ways to find it on any device.
→IP Geolocation: How It Works and How Accurate It Is
How IP addresses map to approximate locations, why city-level accuracy varies, and what VPNs change.
→IP Address Formats: Decimal, Binary, Hex, and How to Convert
Why IP addresses have multiple representations and how to move between them.
→Public vs. Private IP Addresses
What separates public and private address space, NAT, and how traffic gets routed between them.
→IPv4 vs. IPv6: What’s Changing and Why
Address exhaustion, dual-stack networking, and what the transition means for everyday infrastructure.
→How DHCP Works: Discovery to Lease Renewal
The four-step handshake that assigns your device an IP address, and what happens when a lease expires.
DNS
LiveHow DNS Works: A Plain-English Walkthrough
The full DNS resolution chain from browser to authoritative nameserver, step by step.
→DNS Records Explained: A, AAAA, MX, CNAME, TXT, NS
A plain-English breakdown of every common DNS record type and when each one comes into play.
→How Long Does DNS Propagation Take?
Realistic timelines for DNS changes, what TTL actually controls, and how to speed up propagation.
→How to Read a WHOIS Lookup
What each field in a WHOIS or RDAP result means — registrar, nameservers, expiry dates, and abuse contacts.
→RDAP vs. WHOIS: What Changed
Why domain lookups moved from WHOIS to RDAP, and what the switch means for the data you get back.
Subnetting
LiveSubnetting Made Simple: A Beginner’s Guide to CIDR
Learn CIDR notation, subnet masks, and how to divide networks — with worked examples.
→CIDR Notation Explained: How to Read /24, /16, and Everything In Between
What the slash number means, how to calculate the block size, and when you encounter CIDR in the wild.
→VLSM and Supernetting: Beyond Basic Subnetting
Variable-length subnet masks, route aggregation, and when to use them in real network designs.
Security & Email
LiveWhat Is a Firewall? Ports, Rules, and Traffic Filtering
How firewalls use port numbers and rules to control traffic, and how to read a rule set.
→How SSL Certificates Work
The TLS handshake, certificate chains, and why a valid cert on port 443 is only part of the picture.
→What Is Certificate Transparency?
The public logs that record every TLS certificate, the SCTs browsers require, and how to search them.
→Common Network Ports: What They Are and What They Do
A practical overview of well-known ports, what services use them, and why they matter for security.
→TCP vs UDP: What’s the Difference?
Why TCP guarantees delivery, why UDP trades reliability for speed, and which protocol your traffic uses.
→SPF, DKIM, and DMARC Explained
How the three email authentication standards work together to stop spoofing and improve deliverability.
→How to Set Up SPF and DMARC Without Breaking Email
A safe step-by-step process for publishing SPF and DMARC records without disrupting live mail flow.
→What Is a DNS Blacklist?
How DNSBL and RBL lists work, why IPs end up on them, and how to get off one.
→What Is a MAC Address?
How MAC addresses work, where to find yours, and why vendor lookups are useful for network management.
→What Is ARP (Address Resolution Protocol)?
How devices map an IP address to a MAC address on the local network, and what happens when ARP fails.
→Network Basics: The OSI Model in Plain Language
All seven layers explained without the jargon, with real-world examples at each level.
VPN & Privacy
LiveWhat Is a VPN?
How VPNs encrypt your traffic, mask your IP address, and route connections through remote servers.
→VPN Protocols Explained
WireGuard, OpenVPN, IKEv2, and L2TP compared — what each protocol does and when to use it.
→Does a VPN Hide Your IP Address?
What a VPN actually conceals, what it doesn’t, and the cases where your real IP can still leak.
→What Is a DNS Leak?
How DNS requests can escape a VPN tunnel, expose your real ISP, and how to test for and fix leaks.
→VPN vs. Proxy vs. Tor
How the three main anonymity tools differ in speed, security, and the right use case for each.
→Do You Need a VPN on Public Wi-Fi?
The real risks of open networks, what HTTPS already protects, and when a VPN adds meaningful coverage.
→How to Choose a VPN
The criteria that actually matter — jurisdiction, logging policy, protocol support, and speed — with top picks.
Troubleshooting
LiveHow to Troubleshoot Network Connectivity (Step by Step)
The systematic 7-step diagnostic workflow — physical checks through DNS, firewall, and port testing.
→Wi-Fi Connected but No Internet
Why your device shows a connection but pages won’t load, and how to fix it step by step.
→Slow Internet but Speed Test Is Fine
The specific causes behind sluggish browsing when your bandwidth numbers look normal.
→DNS Server Not Responding
What causes this error, how to isolate whether it’s your DNS or your connection, and the fixes that work.
→DNS Probe Finished No Internet
What this Chrome error means, the most common causes, and how to resolve it on Windows and macOS.
→Traceroute Explained
How to read tracert and traceroute output, identify the hop where packets stop, and interpret latency spikes.
→How to Read Ping Results
Every field in ping output explained — RTT, TTL, packet loss, and what each tells you about a connection.
→169.254 IP Address: What It Means and How to Fix It
Why your device assigned itself an APIPA address, what DHCP failure looks like, and how to recover.
→Windows Network Reset Commands
Every ipconfig, netsh, and network-stack reset command in one place, with what each one actually does.
Practical Guides
LiveWhat Is Reverse DNS and When Do You Need It?
How PTR records work, why email deliverability depends on them, and how to check yours.
→How Long Will It Take to Transfer That File?
The bandwidth math behind transfer times, why real speeds differ from advertised, and how to estimate accurately.
→How to Choose a Web Hosting Provider
What actually matters when comparing hosts — performance, support, pricing, and what the specs really mean.
→Best Network Security Software for 2026
A practical comparison of firewalls, antivirus, and network monitoring tools worth paying for this year.
→AI Crawlers, robots.txt, and llms.txt: What to Know
Which AI bots visit your site, what robots.txt actually controls, and why llms.txt is not a standard yet.
Beyond the tools
Our Resources page rounds out the toolkit: the hosting, VPN, and privacy services we actually use, the reference standards we cite, and the free third-party tools worth learning.
Browse our Resources →