DOI prefix

A DOI prefix is the portion of a Digital Object Identifier before the first forward slash, always of the form 10.NNNN: the leading 10 is the directory indicator identifying the identifier as belonging to the DOI system within the underlying Handle System, and NNNN is a numeric (occasionally alphanumeric, for longer-established registrants) string assigned to one specific registrant. In a full identifier such as 10.1038/s41586-021-03819-2, 10.1038 is the prefix and everything after the slash is the suffix, which the registrant itself defines and controls.

Who assigns a prefix, and how

A DOI prefix is issued by a DOI Registration Agency, not by the International DOI Foundation (IDF) directly — the IDF governs the DOI system as a whole, but registration happens through one of several accredited Registration Agencies. For scholarly research outputs the two most relevant are Crossref, used predominantly by journal publishers for articles, and DataCite, used predominantly for datasets, software, and other non-article research outputs. To obtain a prefix an organisation joins the relevant Registration Agency as a member (or works through an existing member acting on its behalf) and is then allocated one or more prefixes to register DOIs under.

What a prefix does and does not tell you

A prefix is unique to its registrant, but the relationship is not always one-to-one and it is not machine-parseable beyond that. A large publisher may hold several prefixes reflecting separate imprints, journals acquired from other publishers, or historical artefacts of past registration decisions — so seeing prefix 10.1038 reliably indicates the DOI was registered by (or on behalf of) Nature Portfolio, but a registrant holding multiple prefixes means the reverse inference (this specific prefix is the only one that publisher uses) does not hold in general. The prefix says nothing on its own about content type, license, article version, or publication date; that information lives in the DOI’s associated metadata record at the Registration Agency, retrievable via content negotiation or the Registration Agency’s API, not encoded in the prefix string itself.

Prefixes are not permanent identity markers

Because a prefix is a registration artefact rather than an immutable property of a publication, it can change when a registrant’s organisational or hosting arrangement changes, even though DOIs already registered under the old prefix continue to resolve. openRxiv (the independent non-profit that now operates bioRxiv and medRxiv, spun out of Cold Spring Harbor Laboratory in March 2025) moved newly posted preprints from the historical 10.1101 prefix to 10.64898 starting December 1, 2025, coinciding with its governance transition; pre-existing 10.1101 DOIs were unaffected and continue to resolve normally. A citation manager, CRIS, or bibliometric tool that hard-codes an assumption like “prefix 10.1101 always means bioRxiv/medRxiv” will silently miss content registered after such a change unless it is updated.

Prefix vs. suffix vs. full DOI

The prefix identifies the registrant; the suffix, chosen entirely by the registrant subject only to basic character-set rules, identifies the specific object within that registrant’s namespace. Neither half alone is a usable, resolvable identifier — only the combined prefix/suffix string, typically expressed as a URL (https://doi.org/10.1038/s41586-021-03819-2), resolves through the DOI system to the object’s current location.

Frequently asked questions

Can one organisation hold more than one DOI prefix?

Yes. Large publishers commonly hold multiple prefixes reflecting different imprints, acquired journals, or legacy registration history; the prefix is unique per registration event, not necessarily per organisation.

Does the prefix tell you whether a DOI was registered with Crossref or DataCite?

Not from the prefix string alone. Both agencies allocate prefixes from the same 10.NNNN namespace; determining which Registration Agency owns a given DOI requires a lookup (for example via the DOI Foundation’s Registration Agency lookup service or the agency-specific API), not inspection of the prefix format itself.

Can a shortDOI substitute for the prefix/suffix structure?

No. A shortDOI is a redirect alias, not a separately registered persistent identifier — it does not follow the standard prefix/suffix syntax and has no independent Registration Agency metadata record. Citation practice expects the full DOI, not a shortDOI alias.

References

• International DOI Foundation, ‘DOI Handbook’.
• Crossref, ‘Prefixes’ documentation (crossref.org).
• DataCite documentation, ‘DOI prefixes and suffixes’.