Potential issue with Diamond Open Access classification in OpenAlex

[Raphael Faria Vilas Boas]

Dear all,

I identified an issue in OpenAlex that may already have been noticed by others, but I believe it is worth bringing to your attention.

When searching for articles produced in Brazil since 2020 and filtering for journals classified as Diamond Open Access, six of the ten journals with the highest publication counts are widely recognized as predatory journals and certainly charge APCs. Since these journals publish thousands of articles, their incorrect classification as Diamond Open Access could introduce a significant bias into scholarly communication analyses based on OpenAlex data.

In this context, I think it is important to understand how this classification is being assigned. Since most of these journals are not indexed in major databases due to their predatory nature, a couple of possibilities come to mind:

• Is OpenAlex automatically classifying journals with no available information about their access model as Diamond Open Access?
• Or is this information being obtained from an external source that allows journals to self-report this attribute, making misleading declarations possible?

If the first hypothesis is correct, it might be more appropriate to classify these journals as "Access status unknown" or "No information available on the access model", rather than assigning them to the Diamond Open Access category.

If, on the other hand, this information comes from an external source, it might be worth considering the DOAJ as the primary reference for identifying Diamond Open Access journals.

I believe it is important to clarify the origin of this classification, as this issue may affect bibliometric studies and analyses of the open access ecosystem, particularly when aggregated OpenAlex data are used.