Network Calculators and APIs

Free online network calculators and APIs for home and corporate networking, presented simply.

We offer free REST APIs for system administrators, network administrators, developers, and home network users. Perform network calculations for subnets and convert between binary, decimal, hexadecimal, and octal. Verify your website DNS records, including SPF, and SSL certificates.

Try the Tools

Subnet Calculator

Look up details of IPv4 subnets and CIDR blocks.

DNS Tools

Look up DNS records for a hostname like ''.

DNS Lookup

Security Tools

Look up security of websites, including TLS/SSL certificates.


Access free REST APIs for subnets, DNS, website security, and binary numbers.

About NetworkCalc

NetworkCalc is a suite of free online resources to help you manage your IP subnets, website security, and home or corporate networks.

We offer a variety of free calculators, utilities, and Application Programming Interfaces (APIs) for:

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