Objective. The article addresses the active disclosure transparency index obtained for 45 Spanish public university archives based on an analysis of their respective websites with TransPa_BA software. Design/Methodology/Approach. TransPa_BA, a tool inspired by Spain's Metodologia de Evaluacion y Seguimiento de la Transparencia [transparency assessment and monitoring method, MESTA], features a total of 22 indicators that measure active public disclosure by archives in keeping with the provisions of the national Transparency Act. Results/Discussion. Although the findings reveal some good practices, on the whole these institutions were observed to furnish scant transparency-targeted information. The areas where they are strongest include the staff directory, regulations for use and the classification chart. None of the archives analysed groups all that information on a page specifically devoted to transparency, however. Conclusions. The TransPa-BA tool can be effectively used to determine the extent to which such university services are committed to active public disclosure. At the same time it encourages collective learning liable to contribute to the gradual disclosure of information that reinforces their transparency or eliminates unnecessary elements, as appropriate. Originality/value. The indicators and their associated parameters (visibility, form, accessibility, reusability, dating and currency) provide guidelines enabling university archives to heighten their transparency and comply more fully with the accountability owed to their primary stakeholders respecting their activities and performance.