Background The Cochrane Library databases are available via different interfaces; evidence in the literature, together with anecdotal evidence, shows interfaces perform differently. To ensure the quality of searches, a study was undertaken to systematically explore the functionality of interfaces. Objectives To demonstrate differences in functionality when searching the same databases across different interfaces; to discuss the implications this may have on searching; and in a wider context, to suggest a ‘best match’ for comparable searching. Methods Detailed cross‐comparisons of a selection of search functions including MeSH terms, free text, proximity operators and truncation were undertaken in databases accessed via CRD, Wiley and Ovid. Up to three terms per function were selected and analysed. Results Differences were identified in the way searches for MeSH headings are executed, which fields are searched, how proximity operators perform, the word order searched and where terms are searched. This adds to a body of evidence demonstrating a lack of consistency in searching across different interfaces. Conclusions A ‘best match’ for comparable searching is suggested. Differences between interfaces offering the same database content can have implications for the success of a search, on user education, and on database evaluation and purchasing decisions.