The 'Big Three' of Scientific Information: A comparative bibliometric review of Web of Science, Scopus, and OpenAlex

The present comparative study examines the three main multidisciplinary bibliographic databases, Web of Science Core Collection, Scopus, and OpenAlex, with the aim of providing up-to-date evidence on coverage, metadata quality, and functional features to help inform strategic decisions in research assessment. The report is structured into two complementary methodological sections. First, it presents a systematic review of recent scholarly literature that investigates record volume, open-access coverage, linguistic diversity, reference coverage, and metadata quality; this is followed by an original bibliometric analysis of the 2015-2024 period that explores longitudinal distribution, document types, thematic profiles, linguistic differences, and overlap between databases. The text concludes with a ten-point executive summary and five recommendations.