@fynlink/nochain

Fast detection of known short URL domains for browser and Node.js runtimes.

Why this package

This package is designed for anti-chain-shortening enforcement (for example, blocking redirects to another known shortener).

• Very fast runtime checks using pre-generated in-memory map lookups
• Browser-safe and Node.js-safe (no runtime dependencies)
• Includes normalization utilities for domain/URL input
• Includes an updater script to regenerate the generated map from the canonical local source list

Installation

npm install @fynlink/nochain

Usage

import { isKnownShortUrlDomain } from '@fynlink/nochain';

isKnownShortUrlDomain('bit.ly'); // true
isKnownShortUrlDomain('https://tinyurl.com/example'); // true
isKnownShortUrlDomain('example.com'); // false

Runtime manual domain list

If your application has extra short domains, create a matcher once with your manual list and reuse it:

import { createShortUrlDomainMatcher } from '@fynlink/nochain';

const isShortUrlDomain = createShortUrlDomainMatcher([
  'manual-short-domain.example',
  'custom.manual-link.test'
]);

isShortUrlDomain('https://manual-short-domain.example/abc'); // true
isShortUrlDomain('sub.custom.manual-link.test'); // true
isShortUrlDomain('https://bit.ly/abc123'); // true (built-in list still applies)
isShortUrlDomain('example.com'); // false

createShortUrlDomainMatcher is a one-time setup for the provided list. If the list changes, create a new matcher instance.

API

• isKnownShortUrlDomain(domainOrUrl: string): boolean
• createShortUrlDomainMatcher(additionalDomains: Iterable<string>): (domainOrUrl: string) => boolean
• normalizeDomain(input: string): string | null
• SHORT_URL_DOMAINS: readonly string[]
• SHORT_URL_DOMAIN_COUNT: number

Data updates

Regenerate the dataset:

npm run update:domains --workspace @fynlink/nochain

Current source inputs are documented in NOTICE and embedded in the generated source file header.