OneRoster, developed by 1EdTech, is a standardized specification designed to facilitate the secure and efficient exchange of roster-related data, course information, and academic performance metrics within K-12/ Primary/ Secondary educational environments. It establishes a structured data model encompassing entities such as users (students and instructors), courses, enrolments, organizational hierarchies, and grade records, ensuring robust interoperability between disparate systems like Student Information Systems (SIS) and Learning Management Systems (LMS). The current iteration, OneRoster 1.2, provides three modular services—Rostering, Gradebook, and Assessment Results—delivered through a RESTful API with JSON payloads or as CSV files for bulk data transfer, allowing institutions to adopt specific components as required. By leveraging these services, OneRoster automates data synchronization, enhances data integrity, and supports real-time updates, serving as a critical framework for integrating heterogeneous edtech solutions and optimizing digital learning ecosystems across European contexts and beyond.