Purpose: Informed by the critical literacy framework, this study aims to investigate how a free online collection website and collection analysis tool (CAT) have been used by educators (e.g. librarians, media specialists) to enhance the diversity of their children's and young adult book collections -- a form of infoactivism. Quantitative and qualitative data were used to identify participants' level of satisfaction using the resources and to what extent these resources influenced their confidence in developing diverse book collections and collaborating with other librarians. Participants' testimonials were used to explore the positive impact of the tool on their working spaces and communities. Design/methodology/approach: A total of 575 educators participated in the study, and a subset of these participants provided feedback on how these tools influenced their confidence in assessing and building diverse book collections. This paper conducted a thematic analysis of participants' responses regarding the impact of these tools on their practice to explore the extent to which educators' critical stances to inquire, reflect and take action (i.e. core components of the critical literacy framework) were represented. Findings: Results indicate that most participants were satisfied with the online collection resources. Despite a few areas for improvement noted by the participants (e.g. content organization and presentation), the tools increased their confidence in assessing racial and cultural diversity; however, the resources did not increase participants' motivation to collaborate on the development of diverse book collections. The thematic analysis showed that although most participants assumed a critical stance to inquire (54.05%), reflect (54.05 %) and take action (62.16%) based on their interaction with the CAT, only 27.03% of their responses reflected all these core components of the critical literacy framework. Originality/value: This study describes a novel approach to support educators' confidence in building diverse book collections, which can impact their libraries and/or communities. Furthermore, it illustrates how critical information literacy can be used as an epistemological lens to investigate collection development processes and their ramifications on social change through critical inquiry, reflection and action.