loading . . . Open Online Courses for Informal Carers: Systematic Integrative Review Background: Informal carers, people providing unpaid support to relatives or close others with an illness, disability, and/or advanced age-related care needs, are key stakeholders in healthcare systems. Carers have their own health and wellbeing challenges, yet their needs and care pathways are often overlooked by health providers. Open online courses offer opportunities to address the information and support needs of large numbers of carers. However, our collective understanding of the design and outcomes of courses and learner experiences is limited. Objective: This systematic integrative review aimed to map the characteristics of open online courses for informal carers, explore learner experiences, and identify barriers and enablers to participation to inform the design of future courses. Methods: Following PRISMA guidelines, we systematically searched four electronic databases (APA PsycINFO, CINAHL, EMBASE, MEDLINE) for articles published from inception to 30 January 2025. Included articles were peer-reviewed, English-language, and reported on the development, delivery, or outcomes of open online courses for informal carers aged 16+ years. Excluded articles had no carer focus or were conference abstracts. Two reviewers independently screened titles and abstracts for eligibility. Backward and forward citation searches were also conducted. Due to study heterogeneity, data on article methodology, course characteristics, and course evaluations were extracted and synthesised narratively, guided by Popay et al. Quality assessments of quantitative articles and the quantitative components of mixed methods articles were conducted using the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool. Qualitative components within mixed methods articles were appraised using the Critical Appraisal Skills Program (CASP) toolkit. Results: Searches identified 201 articles, of which 10 (6 quantitative, 4 mixed methods) met the inclusion criteria. No qualitative articles were identified. All included courses were massive open online courses. Sample sizes ranged from 3 to 17,591 participants, primarily targeting carers of older individuals (n=4). Course durations ranged from 6 to 10 weeks, with common features including discussion forums and quizzes. Completion rates ranged from 42% to 67% (n=5). Five articles reported improved carer knowledge and application of skills. Key enablers to learning included course accessibility and flexibility. Key barriers to learning included limited peer interaction, technical difficulties, time constraints, language challenges, and online privacy challenges. Most articles were of weak quality, except one strong quantitative RCT. Conclusions: The evidence was limited by moderate-to-weak study quality, inconsistent measures, and exclusion of grey literature. Despite these limitations, findings suggest that open online courses may improve carersโ knowledge and skills and enable accessible, flexible learning. However, barriers to learning including limited learner-to-learner interaction within and external to the course, time constraints, and digital or language barriers highlight the need for more inclusive and interactive course designs. Further high-quality research is needed to standardise outcomes and explore long-term impacts. Clinical Trial: PROSPERO CRD42024532766; https://www.crd.york.ac.uk/PROSPERO/view/532766 (08 April 2024) http://dlvr.it/TMkvd3