CIDR Parser

Parse CIDR notation to inspect IPv4 or IPv6 network ranges, masks, and integer boundaries directly in the browser.

CIDR Input
Inspect IPv4 and IPv6 blocks locally in the browser. Paste a host-address CIDR or a canonical network and the parser resolves the real subnet boundaries.

Host bits are allowed. The parser rewrites the block to the canonical network address before showing the range, masks, and integer values.

10.24.8.19/212001:db8:abcd::123/64
Nothing parsed yet
Enter a CIDR block to inspect the canonical network, usable range, and routing values.
Canonical range, numeric boundaries, and routing details for the current CIDR block.

CIDR Parser turns a block like 10.24.8.19/21 or 2001:db8:abcd::123/64 into the network you actually mean. It normalizes host-address input, shows the canonical subnet, and exposes the boundaries you usually need when writing firewall rules, documenting ranges, or checking whether an allocation is larger than intended.

What It Shows

The result starts with a quick overview, then breaks the block into practical details: canonical CIDR, total and usable address counts, range start and end, plus the integer values behind the block. For IPv4, you also get the netmask, wildcard mask, and broadcast address. For IPv6, the parser keeps the same workflow but hides fields that do not apply.

Why Canonicalization Matters

Many pasted CIDR values include host bits. That is fine for humans, but routers, ACLs, and documentation usually need the canonical network address instead. By rewriting the block before you copy anything out, the tool makes it easier to catch off-by-one assumptions before they leak into config.

Practical Notes

  • /31 and /32 IPv4 blocks are treated as fully usable, which matches modern point-to-point and host-route usage.
  • IPv6 blocks report the full address space and usable range without inventing a broadcast concept.
  • Everything runs locally in the browser, so internal subnets do not leave the page while you inspect them.