About CIDR Aggregator

Aggregates (summarizes) a list of IPv4 addresses and CIDR blocks into the smallest set of CIDR routes that covers exactly the same addresses — the operation behind route summarization and firewall/NSG rule consolidation. Adjacent and overlapping blocks merge, contained blocks are absorbed, and each resulting range is decomposed into the minimal number of correctly-aligned CIDR blocks without adding any address that was not in the input. It also reports the single smallest supernet that encloses everything (which may include extra addresses) for cases where one block is acceptable.

• Exact aggregation: merges adjacent/overlapping/contained inputs, never covers addresses you did not list
• Each merged range is split into the fewest aligned CIDR blocks (optimal range-to-CIDR decomposition)
• Accepts bare IPv4 addresses (treated as /32) and CIDR blocks /0–/32, one per line
• Reports input count, aggregated block count, and total addresses covered
• Also computes the smallest single enclosing supernet (over-covers gaps)
• Invalid lines are skipped and listed rather than failing the whole batch

Frequently Asked Questions

How is this different from a CIDR-to-range converter?

A converter expands one block into its address range. This goes the other way: it takes many addresses/blocks and collapses them into the fewest CIDR blocks — what you need for route summarization, ACLs, and security-group rules.

Does aggregation ever include addresses I did not enter?

No. The aggregated list covers exactly your inputs — gaps are preserved, so two /24s with a hole between them stay as two /24s. The separate “smallest supernet” figure is the one that may over-cover, and it is labelled as such.

Can it merge 10.0.0.0/24 and 10.0.1.0/24?

Yes — those are adjacent and aligned, so they aggregate to 10.0.0.0/23. But 10.0.0.0/24 and 10.0.2.0/24 stay separate, since merging them would pull in 10.0.1.0/24, which you did not list.