A persistent URL hosted on the w3id.org domain by the W3C Permanent Identifier Community Group, providing a community-maintained redirect under https://w3id.org/<namespace> to ontologies, vocabularies, and standards documents that may move between hosting providers over time.

ByCASRAI Editorial Board

· Last updated 10 Jul 2026

Examples

Worked examples

Is an instance
https://w3id.org/dpv for the Data Privacy Vocabulary.
Is an instance
https://w3id.org/fair/principles for the FAIR Guiding Principles statement.

Counter-examples

Looks similar, but isn't

Not an instance
A vocabulary served directly from a researcher's personal website is not a w3id.org PURL.
Not an instance
An identifier under purl.archive.org is a different PURL service, not w3id.org.

Editorial commentary

w3id.org is a free, community-run PURL service intended for Web vocabularies, ontologies, and standards. Each namespace is administered through pull requests to a public GitHub repository; redirect rules are expressed in Apache rewrite syntax and reviewed by the community group. The service deliberately stays out of content hosting — it only redirects — and is widely used by the linked-data and FAIR-data communities to provide stable identifiers for ontologies that may be hosted on personal or institutional servers today and elsewhere tomorrow.

References

W3C Permanent Identifier Community Group, 'w3id.org' (w3id.org and github.com/perma-id/w3id.org).

Also known as

w3id

Machine-readable encodings

Use in your systems

JATS XML <role> element

xml

<role vocab="credit"
      vocab-identifier="https://casrai.org/dictionary/"
      vocab-term="w3id.org PURL"
      vocab-term-identifier="https://casrai.org/dictionary/term/w3id-purl" />

Schema.org DefinedTerm (JSON-LD)

json

{
  "@context": "https://schema.org",
  "@type": "DefinedTerm",
  "@id": "https://casrai.org/dictionary/term/w3id-purl",
  "name": "w3id.org PURL",
  "identifier": "https://casrai.org/dictionary/term/w3id-purl",
  "description": "A persistent URL hosted on the w3id.org domain by the W3C Permanent Identifier Community Group, providing a community-maintained redirect under https://w3id.org/<namespace> to ontologies, vocabularies, and standards documents that may move between hosting providers over time.",
  "inDefinedTermSet": "https://casrai.org/dictionary/domain/persistent-identifiers#set",
  "url": "https://casrai.org/dictionary/term/w3id-purl",
  "sameAs": [
    "w3id"
  ],
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "publisher": {
    "@id": "https://casrai.org/#organization"
  },
  "dateModified": "2026-07-10T02:06:20",
  "inLanguage": "en"
}

Referenced across the research world

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