Free networking tools
No sign-up, no limits. And because each tool shares its math with the NetForge-AI simulator, you can take any answer straight into the lab and prove it with a ping.
Subnet Calculator
Network and broadcast address, usable host range, subnet + wildcard mask, address class and type — for any IPv4 CIDR.
Open toolVLSM Planner
Give it one block and your per-subnet host counts; get a largest-first VLSM allocation with every subnet's full breakdown.
Open toolWildcard Mask Converter
Convert between prefix length, subnet mask, and ACL wildcard mask — with a ready-to-paste access-list example.
Open toolWant the theory behind the math? IPv4 Subnetting in 20 minutes is free, hands-on, and opens in the lab.