Network tools built by
network engineers
Fast, free, and precise calculators for subnetting, CIDR planning, and IP addressing. No login. No fluff. Works entirely in your browser.
VLSM Planner
Allocate subnets of varying sizes from a parent block. Enter host requirements and get network/broadcast/range for each — sorted and packed automatically.
Open VLSM Planner →CIDR Calculator
Enter any IPv4 CIDR block and instantly get network address, broadcast, subnet mask, wildcard mask, binary breakdown, and usable host range.
Open CIDR Calc →Subnet Overlap Detector
Paste a list of CIDR blocks and instantly detect overlapping or duplicate networks. Essential for VPN and VPC peering rule audits.
Open Overlap Detector →IP Range → CIDR
Convert any arbitrary start–end IP range into the minimal set of CIDR blocks covering it exactly. Essential for firewall migrations and AWS Security Groups.
Open IP Range Converter →Mask Converter
3-way live converter between subnet mask, wildcard mask, and CIDR prefix. Full 33-row reference table. Type in any field — all others sync instantly.
Open Mask Converter →IPv6 Subnet Calculator
Enter any IPv6 prefix and get the network, first/last address, address count, and both compressed and expanded representations with hextet visualisation.
Open IPv6 Calc →Supernet / Route Aggregator
Paste a list of IPv4 prefixes and get the minimal set of covering supernets using binary-trie folding. Includes route savings count, coverage efficiency, and single covering supernet.
Open Route Aggregator →