@socketregistry/packageurl-js

@socketregistry/packageurl-js

TypeScript Package URL (purl) parser and builder. Drop-in replacement for packageurl-js with full type safety, zero dependencies, and spec compliance with the Package URL specification.

@socketregistry/packageurl-js is the Socket-maintained drop-in replacement for packageurl-js - same API, but ships with built-in TypeScript types, zero runtime dependencies, full purl-spec coverage, and first-class VERS support. It exists because the upstream package lacked types and a maintained tree-shakeable surface; this fork closes both gaps without breaking compatibility.

What is a PURL?

A Package URL (purl) standardizes how to identify software packages:

pkg:npm/lodash@4.17.21
pkg:pypi/requests@2.28.1
pkg:maven/org.springframework/spring-core@5.3.21

Format breakdown:

  pkg:type/namespace/name@version?qualifiers#subpath
  │   │    │         │    │       │          │
  │   │    │         │    │       │          └─ Optional subpath
  │   │    │         │    │       └──────────── Optional key=value pairs
  │   │    │         │    └──────────────────── Optional version
  │   │    │         └───────────────────────── Required package name
  │   │    └─────────────────────────────────── Optional namespace/scope
  │   └──────────────────────────────────────── Required package type
  └──────────────────────────────────────────── Scheme (always "pkg:")

Supports 40+ ecosystems: npm, pypi, maven, gem, cargo, nuget, composer, golang, docker, and more.

Features

• ✅ Modular & tree-shakeable - Import only what you need
• ✅ Full TypeScript support - Comprehensive type exports
• ✅ Zero dependencies - Lightweight and secure
• ✅ Spec compliant - Follows purl-spec v1.0.0, published as ECMA-427
• ✅ 100% test coverage - Over 1,000 passing tests
• ✅ Multiple APIs - Functional, class-based, and builder patterns
• ✅ URL conversion - Convert to repository and download URLs
• ✅ Registry checks - Verify package existence across 17 registries
• ✅ VERS support - First-class implementation of the VERS companion spec (Vers, VersConstraint, VersWildcard)
• ✅ Immutable updates - withVersion, withNamespace, withQualifier, withQualifiers, withSubpath
• ✅ Result-based parsing - tryFromString, tryFromJSON, tryFromObject, isValid, fromUrl

Install

pnpm install @socketregistry/packageurl-js

Drop-in replacement via package override:

{
  "pnpm": {
    "overrides": {
      "packageurl-js": "npm:@socketregistry/packageurl-js@^1"
    }
  }
}

Requirements: Node >= 18.20.8

Usage

Modular Functions (Tree-shakeable)

Parse npm specifiers:

import { parseNpmSpecifier } from '@socketregistry/packageurl-js'

parseNpmSpecifier('lodash@4.17.21')
// -> { namespace: undefined, name: 'lodash', version: '4.17.21' }

parseNpmSpecifier('@babel/core@^7.0.0')
// -> { namespace: '@babel', name: 'core', version: '7.0.0' }

Stringify and compare - stringify, equals, compare

import { compare, equals, stringify } from '@socketregistry/packageurl-js'

stringify(purl)
// -> 'pkg:npm/lodash@4.17.21'

equals(purl1, purl2) // -> boolean
compare(purl1, purl2) // -> -1 | 0 | 1

compare returns a sort-friendly ordering, so an array of PURLs sorts with purls.sort(compare).

Class API

Parse and build:

import { PackageURL } from '@socketregistry/packageurl-js'

// Parse strings
const purl = PackageURL.fromString('pkg:npm/lodash@4.17.21')
console.log(purl.name) // 'lodash'
console.log(purl.version) // '4.17.21'

// Parse npm specifiers
PackageURL.fromNpm('lodash@4.17.21')
PackageURL.fromNpm('@babel/core@^7.0.0')

// Constructor
new PackageURL('npm', null, 'express', '4.18.2')
// -> 'pkg:npm/express@4.18.2'

Builder pattern - PurlBuilder, for assembling a PURL piece by piece

import { PurlBuilder } from '@socketregistry/packageurl-js'

PurlBuilder.npm().name('lodash').version('4.17.21').build()
// -> 'pkg:npm/lodash@4.17.21'

URL conversion - PURL to repository/download URL, and back from a URL or bare filename

import { UrlConverter } from '@socketregistry/packageurl-js'

// PackageURL -> URL
UrlConverter.toRepositoryUrl(purl)
// -> 'https://github.com/lodash/lodash'

UrlConverter.toDownloadUrl(purl)
// -> 'https://registry.npmjs.org/lodash/-/lodash-4.17.21.tgz'

// URL -> PackageURL
UrlConverter.fromUrl('https://www.npmjs.com/package/lodash')
// -> PackageURL for pkg:npm/lodash

// fromUrl also recognizes distribution (download) URLs and bare paths
UrlConverter.fromUrl(
  '/packages/orjson-3.11.9-cp314-cp314-manylinux_2_17_x86_64.whl',
)
// -> PackageURL for pkg:pypi/orjson@3.11.9

fromUrl tries hostname-based parsers first, then falls back to distribution-filename parsing. The individual parsers are also exposed when you know the shape:

// Per-ecosystem aggregators (try the ecosystem's known URL shapes)
UrlConverter.fromNpmUrl(url) // registry metadata/tarball or npmjs.com page
UrlConverter.fromPypiUrl(url) // project page or wheel/sdist filename
UrlConverter.fromGemUrl(url) // gem page or .gem / .gemspec.rz
UrlConverter.fromGolangUrl(url) // pkg.go.dev page or module-proxy archive
UrlConverter.fromCargoUrl(url) // crate page or download path

// Distribution (download) URLs/paths, host-independent
UrlConverter.fromDownloadUrl(
  '/packages/numpy-2.3.0-cp313-cp313-macosx_11_0_arm64.whl',
)
// -> PackageURL for pkg:pypi/numpy@2.3.0

// Single-shape host parsers: fromGitHubUrl, fromGitlabUrl, fromBitbucketUrl,
// fromComposerUrl, fromHexUrl, fromPubUrl, fromDockerUrl, fromCocoapodsUrl,
// fromHackageUrl, fromCranUrl, fromCondaUrl, fromCpanUrl, fromHuggingfaceUrl,
// fromLuarocksUrl, fromSwiftUrl, fromVscodeMarketplaceUrl, fromOpenVsxUrl

Registry existence checks - does this package actually exist, across 17 registries

Network calls, so they live in a separate /exists entry point and stay out of the main bundle.

import { purlExists, npmExists } from '@socketregistry/packageurl-js/exists'

// Check if package exists in its registry
await purlExists(purl)
// -> { exists: true, latestVersion: '4.17.21' }

// Type-specific checks (modular)
await npmExists('lodash')
await npmExists('core', { namespace: '@babel' }) // scoped package
await npmExists('lodash', { version: '4.17.21' }) // validate version

// Supported registries:
// npmExists, pypiExists, cargoExists, gemExists,
// mavenExists, nugetExists, golangExists, packagistExists,
// cocoapodsExists, pubExists, hexExists, cpanExists,
// cranExists, hackageExists, condaExists, dockerExists,
// vscodeExtensionExists

VERS (Version Range Specifier)

First-class implementation of the VERS companion spec:

import { Vers } from '@socketregistry/packageurl-js'

const range = Vers.parse('vers:npm/>=1.0.0|<2.0.0')
range.contains('1.5.0') // -> true
range.contains('2.0.0') // -> false

Immutable updates

PackageURL instances are immutable; with* methods return a new instance:

const next = purl
  .withVersion('5.0.0')
  .withQualifier('repository_url', 'https://github.com/lodash/lodash')

Result-based parsing

Parse untrusted input without try/catch:

import { PackageURL } from '@socketregistry/packageurl-js'

const result = PackageURL.tryFromString(userInput)
if (result.isOk()) {
  use(result.value)
} else {
  log(result.error)
}

PackageURL.isValid(userInput) // -> boolean
PackageURL.fromUrl('https://github.com/lodash/lodash') // infers purl from URL

// fromUrl also recognizes distribution (download) URLs and bare paths:
// wheels, sdists, tarballs, gems, and module-proxy archives.
PackageURL.fromUrl(
  '/packages/orjson-3.11.9-cp314-cp314-manylinux_2_17_x86_64.whl',
) // -> pkg:pypi/orjson@3.11.9

TypeScript Types

Every type is exported, so nothing needs to be re-declared to annotate a value this library hands back.

Type imports - PackageURLObject, NpmPackageComponents, and the rest

import type {
  ComponentEncoder,
  DownloadUrl,
  NpmPackageComponents,
  PackageURLObject,
  ParsedPurlComponents,
  QualifiersObject,
  RepositoryUrl,
} from '@socketregistry/packageurl-js'

// Type-safe npm package parsing
const components: NpmPackageComponents = parseNpmSpecifier('lodash@4.17.21')

// Type-safe PURL objects
const obj: PackageURLObject = purl.toObject()

Constants - PurlQualifierNames and PURL_Type, instead of bare strings

import { PURL_Type, PurlQualifierNames } from '@socketregistry/packageurl-js'

// Standard qualifier keys
PurlQualifierNames.Checksum // 'checksum'
PurlQualifierNames.RepositoryUrl // 'repository_url'

// Package types
PURL_Type.NPM // 'npm'
PURL_Type.PYPI // 'pypi'

See docs/types.md for the complete type reference.

API Reference

• docs/api.md - Complete API documentation
• docs/types.md - TypeScript type reference

Development

Contributor commands

pnpm install   # Install dependencies
pnpm build     # Build
pnpm test      # Test
pnpm check     # Lint + typecheck

License

MIT