<p>Many online archives, particularly those aggregates collectively built by multiple archival organizations, face financial challenges once their initial grant funding is depleted. This paper examines the financial sustainability of such online archives through the lens of the free-rider problem, a concept from public goods economics. The study introduces relevant economic theories, reviews sustainability literature in the cultural heritage sector, and assesses current revenue generation strategies employed by thirteen sustainable public goods. Drawing from these analyses, this paper proposes actionable strategies for addressing the free-rider problem and sustaining collectively built online archives as public goods.</p>