Support NetworkCalc
Free tools, kept free and independent by the people who find them useful.
NetworkCalc is a free suite of network tools and APIs — subnet calculation, DNS lookups, security checks, and more — built for anyone who needs quick, reliable answers without creating an account or hitting a paywall.
The project is independently built and maintained by Matthew Fisher. There's no paid tier and no current plans to add one — NetworkCalc stays free and open, kept running through the support of people who find it useful.
The public APIs are actively maintained, but offered without a formal uptime SLA. If something looks broken, check the release notes or reach out.