CIDR aggregator
Combine overlapping and adjacent IPv4 CIDRs without adding addresses to the result.
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Networking tools
IP and subnet arithmetic without contacting anything.
CIDR contains IP
Check IPv4 and IPv6 addresses against a CIDR range with a visual prefix comparison.
CIDR splitter
Split an IPv4 network into equal subnets and inspect each address range.
IPv4 number converter
Convert IPv4 addresses to unsigned integers, hexadecimal and binary with editable bits.
IPv4 range to CIDR
Turn an inclusive IPv4 address range into the smallest exact set of CIDR blocks.
IPv4 subnet calculator
Explore an IPv4 network, its subnet mask, address range and host counts.
IPv6 address converter
Compress and expand IPv6 addresses, and inspect all eight hexadecimal groups.
MAC address formatter
Format a 48-bit MAC address and inspect its bytes and address flags.
Aggregate CIDR blocks, test membership, split networks, convert between IPv4 integers and notation, turn ranges into exact CIDR sets, expand IPv6 addresses, and format MAC addresses.
These tools inspect notation and ranges. They never scan, ping, or resolve an address.
Subnetting and address ranges
The IPv4 subnet calculator shows the network, mask, broadcast address, and usable host range for any address and prefix. It is the reference tool for planning or checking a network. The CIDR splitter divides a block into equal subnets for VLANs, sites, or cloud availability zones. The aggregator combines adjacent and overlapping blocks into the shortest exact list, and the range-to-CIDR tool converts a start–end range into the CIDR blocks that firewalls and cloud security groups require.
CIDR contains IP checks whether IPv4 or IPv6 addresses fall inside a range, which is the question behind every allow-list and access rule.
Addresses in every notation
The same address can be written in several ways. IPv4 addresses appear as dotted decimal, 32-bit integers in databases, or hexadecimal in packet dumps, and the IPv4 number converter translates between them. IPv6 addresses have a compressed and an expanded form, and the IPv6 converter produces the canonical RFC 5952 spelling. MAC addresses use colons, hyphens, or dots depending on the vendor, and the MAC formatter normalizes them and explains the flag bits.
These tools calculate with notation only. They never ping, scan, or resolve an address, so they are safe to use with production IP plans and customer data.