Examples
Worked examples
- Is an instance
https://w3id.org/dpv (a W3C Permanent Identifier Community Group PURL for the Data Privacy Vocabulary).
- Is an instance
An archive.org-style PURL redirecting an old URL to its current location.
Editorial commentary
PURLs were introduced by OCLC in 1995 to address link rot on the early Web: rather than citing a resource’s actual location, a citer references a stable PURL, and the service’s maintainer keeps the underlying redirect target current as the resource moves. OCLC operated the original purl.org service for over two decades before transferring it to the Internet Archive on 27 September 2016, which now runs it (and the purl.com/purl.net aliases) as purl.archive.org.
PURL vs. an identifier scheme
A PURL is not a persistent identifier scheme in the sense Identifier scheme describes — there is no formal minting-authority structure, no mandatory accompanying metadata schema, and no registered syntax beyond ‘any HTTP URL.’ It is simply a maintained redirect, which makes it easy to deploy but dependent entirely on the maintaining organisation’s continuity — the opposite trade-off to a DOI or ARK, where persistence is underwritten by a formal registry and governance structure rather than one operator’s redirect table.
Where this shows up in research infrastructure today
Few institutional repositories mint new PURLs directly today, but the pattern lives on in two places a research-data or metadata specialist is likely to encounter it: some older institutional repository deposits (particularly mid-2000s DSpace and Fedora installations) still expose legacy PURL-style identifiers, and w3id.org, run by the W3C Permanent Identifier Community Group, uses the identical redirect pattern to give ontology and vocabulary maintainers a stable namespace URI independent of where the vocabulary document is actually hosted — the mechanism behind many linked-data and metadata-schema URIs referenced from RDM and CRIS systems.
Scope note: PURL’s technical operation — redirect-table configuration, HTTP status-code semantics — is web-infrastructure territory covered authoritatively by the maintaining services themselves; this entry focuses on why a research-administration or repository context encounters the term at all.
References
- Shafer K., Weibel S., Jul E., Fausey J., ‘Introduction to Persistent Uniform Resource Locators’, OCLC, 1996.
- Internet Archive, ‘Persistent URL service purl.org now run by the Internet Archive’, 2016.
Also known as
Persistent Uniform Resource Locator · Persistent URL
Machine-readable encodings
Use in your systems
<role vocab="credit"
vocab-identifier="https://casrai.org/dictionary/"
vocab-term="PURL"
vocab-term-identifier="https://casrai.org/dictionary/term/purl" />{
"@context": "https://schema.org",
"@type": "DefinedTerm",
"@id": "https://casrai.org/dictionary/term/purl",
"name": "PURL",
"identifier": "https://casrai.org/dictionary/term/purl",
"description": "Persistent Uniform Resource Locator, a URL maintained by a PURL service that redirects (typically via HTTP 302) to the current location of the named resource, allowing the persistent URL to remain stable as the underlying resource location changes.",
"inDefinedTermSet": "https://casrai.org/dictionary/domain/persistent-identifiers#set",
"url": "https://casrai.org/dictionary/term/purl",
"sameAs": [
"Persistent Uniform Resource Locator",
"Persistent URL"
],
"license": "https://creativecommons.org/licenses/by/4.0/",
"publisher": {
"@id": "https://casrai.org/#organization"
},
"author": {
"@id": "https://casrai.org/#editorial-team"
},
"datePublished": "2026-05-21T02:10:50",
"dateModified": "2026-08-22T16:17:01",
"inLanguage": "en-GB",
"isAccessibleForFree": true
}
