Enter a DOI, PubMed ID, ISBN, arXiv ID, or other scholarly identifier. The tool checks whether it is well-formed and whether it resolves to a real publication.
Enter a single identifier to check if it is valid and resolvable.
Here are three example inputs showing the different outcomes the validator can return.
Input: 10.1056/NEJMoa2033700
Type: DOI
Title: Dexamethasone in hospitalized patients with Covid-19
Source: CrossRef
Input: 10.9999/doesnotexist
Type: DOI
Well-formed DOI but could not be verified against upstream sources.
Input: hello world
Not recognised as a scholarly identifier.
The validator performs two checks. First, it detects whether the input matches the format of a known scholarly identifier (DOI, PMID, PMCID, ISBN, arXiv, ISSN, or ADS bibcode). This is a syntactic check — it confirms the identifier is well-formed. Second, it attempts to resolve the identifier against the appropriate upstream database (CrossRef for DOIs, PubMed for PMIDs, etc.) to verify that it points to a real publication.
An identifier can be valid but not resolvable — for example, a correctly formatted DOI that has not been registered, or a PMID for a record that has been withdrawn. The tool distinguishes between these cases so you know exactly what to fix.
10.1038/s41586-023-05881-4)36859578)PMC9977688)2301.07041)