ip-range-list

A dependency-free IP allowlist/blocklist. Think Node.js net.BlockList, but faster. Accepts IPv4 and IPv6 addresses, ranges, and subnets, and uses binary search for fast lookups.

Install

npm install ip-range-list

In client-side applications, you can import the package directly via jsDelivr CDN.

Usage

Using the package in ESM/CJS applications:

import { IPRangeList } from 'ip-range-list';

let ranges = new IPRangeList()
    .addRange('192.0.1.1', '192.0.1.255')
    .addSubnet('192.0.2.9/24')
    .addAddress('2001:db8::1');

ranges.contains('192.0.2.42'); // => true
ranges.contains('::ffff:192.0.2.42'); // => true
ranges.contains('2001:db8::2'); // => false

Using the UMD build:

const { IPRangeList } = window.ipRangeList;
let ranges = new IPRangeList();

API

Note

IPv4-mapped IPv6 addresses such as ::ffff:192.0.2.1 are treated as equivalent to plain IPv4 addresses such as 192.0.2.1 across all methods.

new IPRangeList()

Creates an empty mutable list.

.addAddress(address)

Adds one IPv4 or IPv6 address and returns the same list.

.addRange(start, end)

Adds the inclusive range between two addresses and returns the same list.

.addSubnet(cidr)

Adds a CIDR subnet and returns the same list. Host bits are normalized, so 192.0.2.9/24 adds 192.0.2.0 through 192.0.2.255.

.contains(address) and .check(address)

Return whether an address belongs to a stored range. .check() is an alias for .contains(). Invalid candidates return false.

.ranges

A read-only snapshot of the currently stored canonical merged ranges:

[
    {
        start: '::ffff:192.0.2.0',
        end: '::ffff:192.0.2.255',
    },
]

Normalization and errors

• Overlapping and adjacent ranges merge into one canonical inclusive interval.
• IPv4 is stored as IPv4-mapped IPv6 (::ffff:0:0/96), so dotted IPv4 and mapped IPv6 candidates compare identically.
• Public mutation methods reject malformed addresses and unsupported input types with TypeError.
• Out-of-range CIDR prefix lengths and reversed ranges throw RangeError.

Lookups use binary search over the canonical ranges.

Benchmark

The package includes a benchmark comparing IPRangeList with Node.js net.BlockList against Manycast IPv4 and IPv6 prefix data. See the benchmark notes for the data download script, query profiles, methodology, and reproduction steps. The published run used 55,473 prefixes: 41,207 IPv4 prefixes and 14,266 IPv6 prefixes.

The present profile checks addresses from the dataset prefixes, the missing profile checks generated addresses outside the loaded ranges, and the mixed profile uses 20% present addresses and 80% missing addresses.

Scenario	Profile	ip-range-list	node:net BlockList	Result
Full import	-	54.09 ms	40.36 ms	BlockList 1.34x faster
1,000,000 lookups after import	present	1,472.24 ms	184,395.46 ms	ip-range-list 125.25x faster
1,000,000 lookups after import	missing	1,568.54 ms	394,476.87 ms	ip-range-list 251.49x faster
1,000,000 lookups after import	mixed	1,609.40 ms	356,680.64 ms	ip-range-list 221.62x faster
Interleaved import/lookups	present	71.01 ms	1,009.32 ms	ip-range-list 14.21x faster
Interleaved import/lookups	missing	96.28 ms	2,023.87 ms	ip-range-list 21.02x faster
Interleaved import/lookups	mixed	98.54 ms	1,818.27 ms	ip-range-list 18.45x faster

Development

Refer to the contributing guide.