Abstract The Generalist Repository Ecosystem Initiative (GREI) is an effort supported by the National Institutes of Health (NIH) to align seven generalist repositories, and develop shared capabilities, services, metrics, and infrastructure to support data sharing while promoting principles that make data findable, accessible, interoperable and reusable (FAIR). Here we show how coopetition (a partnership approach combining cooperation and competition) provided a model for these seven competing actors to generate common value beyond what each could individually achieve. This approach helped address system-wide challenges encountered when developing an open science ecosystem with multiple competing actors. Simultaneously, coopetition supports research reproducibility, encourages data reuse, and prevents data duplication across repositories. Ultimately, the coopetition model itself emerges as a defining outcome for GREI, enabling a cost-effective, impactful, and sustainable catalyst in the FAIR data ecosystem.