Network Engineer Toolbox
Practical network calculations, diagnostics, and references.
A collection of tools for subnetting, DNS, email authentication, encoding, cryptography, and everyday network engineering tasks.
Subnet calculator
Calculate an IPv4 network from CIDR notation.
IP address
192.168.10.42/24Network
192.168.10.0/24- Broadcast address
192.168.10.255- Subnet mask
255.255.255.0- Usable host range
192.168.10.1 – 192.168.10.254- Usable hosts
254
Tools
Everything in one clear directory.
Choose a category, then open the workspace to use any of the 22 available tools.
IP & Subnet
Address planning, masks, ranges, and wildcard math.
Subnet CalculatorCalculate network boundaries, masks, and usable host ranges.PopularCIDR to Subnet MaskConvert a prefix length to dotted-decimal notation.Subnet Mask to CIDRValidate a subnet mask and resolve its prefix length.IP Range CalculatorMeasure a start/end range and total address capacity.Wildcard Mask CalculatorGenerate the inverse mask used by ACLs and routing protocols.
DNS
Live DNS-over-HTTPS record inspection and reverse lookup.
SPF, DKIM, DMARC, and mail-path diagnostics.
SPF Record CheckerInspect mechanisms, lookup pressure, and terminal policy.PopularDKIM Selector HelperBuild and query selector-specific DKIM record names.DMARC Record CheckerInspect DMARC policy, reporting, and alignment settings.Email Header AnalyzerParse authentication verdicts, identities, and received hops.
Network
Ports, VLANs, CIDR, IP, and HTTP quick references.
Port ReferenceSearch common TCP and UDP ports and service notes.CIDR Reference TableCompare masks, address capacity, and usable host counts.Private / Public IP ReferenceClassify IPv4 ranges and reserved address space.VLAN ID ReferenceQuick guidance for normal, reserved, and extended VLAN ranges.HTTP Status ReferenceSearch response codes by class, meaning, or number.
Utilities
Encoding, cryptography, hashes, and structured-data utilities.
Base64 Encode / DecodeTransform UTF-8 text locally in your browser.URL Encode / DecodeEncode or decode query values and URL components.Encode & Crypto LabWork with ten encoding, hashing, authentication, encryption, and key-derivation methods.PopularJSON Formatter / ValidatorValidate, format, and minify JSON payloads.
Built for everyday work
Engineering depth, without the visual noise.
Calculations stay detailed, technical values stay readable, and every screen is designed to help you reach the next useful answer.
Start with the subnet calculator