Network & DevOps Toolkit
Subnet calculators, TCP MSS/MTU sizing, DNS/WHOIS lookup, and Nmap command builders for engineers
Tools in This Collection
Subnet Calculator
IPv4 subnet calculator with CIDR support — compute network address, broadcast, mask, and host range instantly, right in your browser.
DNS Lookup
Perform DNS lookups and view DNS records
HTTP Headers Viewer
View and analyze HTTP headers
IP Range Calculator
Calculate IP ranges and subnet information
SPF Record Builder
Build and validate SPF DNS TXT records
Port Number Lookup
Look up well-known TCP and UDP ports by number or service name with protocol, description and common-risk flags from a bundled IANA-based dataset of 60+ ports. Fully offline in your browser.
Nmap Command Generator
Compose nmap scan commands from visual pickers of target, scan type, ports, timing template and verbosity, with plain-English explanations for every flag and copy-paste output, for authorized network reconnaissance.
TCP MSS & MTU Calculator
Compute optimal TCP MSS from MTU across Ethernet, PPPoE, GRE, VXLAN, OpenVPN, WireGuard and IPsec tunnels, with per-encapsulation overhead chart, fragmentation-avoidance guidance and a ping -M do path-MTU probe command.
Why This Collection
We curated this collection by combining the best tools for development to match your needs.
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Last updated: October 21, 2026