Practitioner-built, privacy-first
The network and security toolbox that keeps your data on your machine.
Subnet math, DNS and email diagnostics, certificate inspection, and more, computed locally in your browser. No upload, no logging, no account required for the everyday tools.
Built by someone who has done the work since 1996.
Thirty years in enterprise networking and security, delivered as a working instructor rather than a marketing page. Certified across four platforms, so the comparisons here are made honestly, not sold.
Four platforms, taught and held current.
Why local-first matters for security work.
When you paste a configuration, a packet capture, or a certificate into a tool, that data often contains secrets. Here, the everyday tools run entirely in your browser. The input never leaves your device, so there is nothing to log, leak, or subpoena.
Try a tool right now.
The CIDR calculator below runs locally. Type a network and prefix to see the address range, host count, and mask. Nothing is sent anywhere.
CIDR Calculator
Analyze a single IPv4 CIDR block: network, broadcast, mask, and host range.
Runs locally. Nothing is sent to any server.