DOIs, as you probably know, are a tool that organizations can use to register metadata for scholarly materials they publish. When an organization registers a DOI, what they are doing is submitting metadata for that material to a registration agency (RA) like Crossref. That metadata includes things like the material’s title, publication date, authors, and, crucially, the URL where the material can be accessed. Once registered, anyone else may then access the material’s landing page at its current URL by resolving the DOI.
Crossref is not the only RA for DOIs. There are currently 12 RAs worldwide, operating autonomously but linked via membership through the DOI Foundation and our shared adherence to agreed-upon DOI practices and protocols. Most of these RAs allow for the registration of DOIs for scholarly works, but a few RAs specialize in the registration of DOIs for other works, like music and films, or construction materials.
When we review new applications to join Crossref, we check to see which journals, books, etc. an applicant will be registering DOI records for. This lets us identify if materials are already registered in Crossref with another member (and thus require a title transfer) and helps us ensure that all materials have a suitable landing page.
In the course of these checks, we occasionally see that an applicant is displaying something that looks like a DOI but isn’t really a DOI! These are fake DOI-like strings and they are provided by a variety of entities. These fake DOI-like strings range from pretty unconvincing to nearly identical to legitimate DOIs.
We assume good faith when we see that an applicant is using these fake DOI-like strings, as often the issuing entities behind these fake “DOIs” try to pass them off as bona fide. However, we will not accept a membership application from a publisher using fake DOI-like strings and will ask any applicant using them to remove all traces of these fake “DOIs” from their websites, including from existing article PDFs anywhere online, before proceeding with their membership application.
How can you know if a DOI is real or fake?
The easiest way is to resolve it. Entering the DOI after https://doi.org/ should take you to a working landing page. Let’s take the example of 10.1201/9781003455332; pasting this DOI (https://doi.org/10.1201/9781003455332) into a browser takes you to the landing page for the book Yak Milk, exactly as the publisher intended.
Many providers of these fake DOI-like strings have websites with similar domains to doi.org. The DOI Foundation lists several known fake DOI-like string providers, and others doubtless exist. (You can also alert the DOI Foundation if you spot a new provider purporting to offer legitimate DOIs by emailing them at info@doi.org.) Many of these domains are doi.org lookalikes which add an additional letter to the DOI Foundation’s domain or use a TLD other than .org. These sites will ask you to resolve their fake “DOIs” via their own sites rather than via doi.org. This is a hint that something presented as a DOI may not, in fact, be one.
Structurally, legitimate DOIs follow an identical basic pattern: a 10 followed by a period, followed by a four- or five-digit number greater than 999, followed by a slash, followed by a suffix. Here are a few strings that could never be DOIs because they do not follow this pattern:
100.1234/abc- DOIs cannot begin with anything other than 10.10.123/abc- DOIs cannot have three-digit prefixes (123)10.0123/abc- DOI prefixes cannot begin with 010.abcd/123- DOI prefixes will only ever be numerals10/1234/abc- DOIs always begin with a 10 followed by a period, not any other character
You’ll notice that some fake DOI-like strings do not obey these pattern rules. For instance, 7.000100/EIJTEM looks sort of like a real DOI, but begins with a seven! This is an instant at-a-glance giveaway that a “DOI” is not real.
For any DOI prefix (10.#####), you can identify the RA its owner belongs to by resolving just the prefix on doi.org. For example, https://doi.org/10.22034 shows that 10.22034 is a mEDRA prefix:
Whereas https://doi.org/10.71221 shows that 10.71221 is a Crossref prefix:
What about prefix 10.100000? Querying this prefix (https://doi.org/10.100000) instead results in a DOI Not Found page:
While 10.100000 is a potentially valid DOI prefix, it has not yet been created and assigned to an RA. (The highest DOI prefixes as of December 2025 are in the 10.80000s.) 10.100000 may someday be a DOI prefix but it isn’t one as of today. You can always check a DOI prefix this way if you’re unsure if a DOI is real or not.
As with everything, there are a few nuances to consider. Sometimes, resolving a DOI may result in an error page on the DOI Foundation website like this:
Checking
10.5555 reveals that this is a Crossref DOI prefix, so what’s going on?
Sometimes members assign DOIs to their publications but never actually get around to registering them with their RA. This happens a lot when journal publishers are using a platform like OJS, which assigns DOIs automatically but may not deposit them to Crossref automatically. These registrations may also be disrupted if the member who owns prefix 10.5555 doesn’t pay their outstanding fees to Crossref, or if they have misconfigured their depositor credentials in their OJS installation. In these cases, we wouldn’t consider this a fake DOI; instead, we would consider this to be an unregistered DOI. If you ever come across one of these, you may report them via the Report An Error form at the bottom of the error page:
A report will be sent to the member who owns prefix
10.5555, and another report will be sent to you a day after the member has registered the DOI.
You may also sometimes resolve a legitimate DOI that takes you to a 403 or 404 error page, a blank page, or a domain with content different than expected (such as a gambling site). When this happens, it doesn’t mean that the DOI is fake; instead, what it usually means is that this was a properly registered DOI that needs to have its landing page URL updated. To resolve these errors you can post here on our Community Forum or contact our Support team directly. We’ll follow up with the member to try and help them get their DOIs’ landing page URLs up to date.
Very occasionally, you will find a link that appears in every way to be a real DOI, like this one: https://doi.org/10.1234/ThisIsARealDOITrustMe and when you click on it, it takes you to a landing page. However, closer examination reveals this isn’t a real DOI at all; it’s just a hyperlink to the target URL. You’ll note that attempting to legitimately resolve the DOI (by pasting it into a browser, rather than just clicking the link where you see it) will result in a DOI Foundation error page. If you spot a publisher engaging in this practice, please contact us to let us know.
To be very clear: Crossref and the other eleven registration agencies do not have a monopoly on the concept of persistent identifiers for scholarly materials. Many alternative persistent IDs exist and are used in a variety of purposes within the scholarly space: Handles (10524/331) Wikidata IDs (Q57088819), ERIC numbers (EJ1428832), PMCs and PMIDs (38524999), OCLC numbers (10256067864) and too many more to name. Oftentimes these are used in conjunction with DOIs.
What concerns us is the propagation of identifiers masquerading as true digital object identifiers. DOIs are more than just hyperlinks; behind each DOI is a rich and updatable metadata record provided by the object’s publisher that helps people and machines track the antecedents and impacts of research outputs throughout the research nexus. Fake DOIs do not provide these same benefits for their users or the wider scholarly community.
If you have any questions about fake DOIs (including if you’d help to identify if a DOI is real or not), let me know in the comments!