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ARK Alliance

Home of the Archival Resource Key (ARK)

About ARKs

Did you know…

  • … that ARK is a PID (Persistent IDentifier), along with DOI, ORCID, and ROR?
  • … that ARK may be the fastest growing PID scheme you’ve never heard of?
  • … that an average of 5 new ARK organizations are registered every week?
  • … that the ARK scheme is more than 25 years old?
  • … that no one has to pay for the right to create ARKs?
  • … that there are over 15.3 billion ARKs in the world?
  • … that ARK organizations include universities, journals, national libraries, national and regional archives, and fine art and natural history museums?

Archival Resource Key (ARK) identifiers are URLs that support long-term access to information. Learn below what you need to know about ARKs, whether you’re planning how your system or collection will use them, or you’re a developer building ARK tools.

ARK anatomy

An example ARK URL divided into its resolver, ARK label, NAAN, assigned name, sub-part, and variant components.
A labeled example of the parts of an ARK URL.

In the example, https://example.org/ is the replaceable resolver service, or Name Mapping Authority (NMA). The stable ARK begins with ark:, which marks the identifier scheme, followed by the NAAN 12345. The assigned name x54xz321 is unique within that NAAN, and its initial shoulder /x5 defines a sub-namespace. The full base object name is ark:12345/x54xz321. The /s3/f8 qualifiers identify contained sub-parts, and .05v.tiff identifies a variant.

Frequently Asked Questions (FAQs)

ARK FAQs in English, French, and Spanish

ARK overview

  • What ARKs are and why you would use them
  • Identifiers and persistent identifiers (PIDs)
  • Resolvers
  • ARK structure
  • How people are using ARKs
  • Persistence means persistent management
  • ARK Community Code of Conduct

Why ARKs?

  • By 2001 there were 4 major PID types – this is why a 5th was needed.

ARK NAANs and systems

ARK features

  • Shoulders (local namespaces)
  • Metadata
  • Inflections: metadata and policy statement
  • Deleting ARKS

Comparing ARKs, DOIs and other identifier systems

  • Reasons to use ARKs as compared to DOIs
  • What ARK, DOI, Handle, PURL, and URN have in common
  • How ARKs differ from identifiers like DOIs, Handles, PURLs, and URNs
  • Using multiple identifier systems
  • When to use ARKs compared to DOIs, Handles, PURLs, or URNs

Getting started: what to plan for as you implement ARKs

  • Get a Name Assigning Authority Number (NAAN)
  • Decide what ARK features you need
  • Choose (or build) an ARK system

The following in-depth information will be useful if you’re extending your own local repository or system with Noid software to support ARKs, or if you’re developing an ARK system.

General identifier concepts and conventions

  • Terminology
  • NAANs, prefixes, bases, and suffixes
  • Shoulder practices
  • Name Mapping Authority (NMA) services
  • Resolution, N2T, Opacity, Test identifier conventions
  • Base identifier extensions
  • The “NCDA” check character convention

Running minters and resolvers

  • Minting ARK name strings
  • Best practices for minting ARK name strings
  • Opaque identifiers
  • Making server content addressable with ARKs
  • ARK citation format
  • ARK inflection vs. content negotiation

More about the N2T global resolver

  • How N2T works
  • N2T is not just for ARKs

ARK namespaces and sub-namespaces

  • ARK namespace overview
  • ARK shoulder as namespace
  • Shared NAANs
  • The NAAN’s role in N2T ARK resolution
  • How to make changes to a NAAN

More about ARK shoulders

  • Shoulder format
  • Implementing shoulders

Testing ARKs with N2T

  • Test with your own NAAN
  • Request a shoulder under a shared NAAN

ARK implementation best practices

  • ARK creation and object lifecycle
  • Metadata
  • Policy statements