Proceedings of the International scientific and practical conference ―Science in the Modern World‖ (May 4-6, 2026) / Publisher website: www.naukainfo.com. – Barcelona, Spain, 2026. - 260 p.

68 COMPUTER AND SOFTWARE ENGINEERING UDC 004.415.5:004.78 Kutaiev Serhii Valentynovych senior lecturer Lviv State University of Internal Affairs Lviv, Ukraine METHODOLOGY OF HYBRID DATAVALIDATION THROUGH SYNCHRONIZATION OF DESKTOP UI TESTING AND REST API LAYER Abstract. The modern approach to ensuring the quality of complex desktop solutions requires the integration of multi-layered verification strategies. One of the main challenges in E2E (End-to-End) automation is the significant time overhead associated with UI updates and the inherent instability of graphical elements. This paper presents a methodology for hybrid data validation, which combines UI-driven automation (Appium/WinAppDriver) with direct state verification through the REST API layer. The proposed architectural pattern involves validating system state changes, initiated via the desktop interface, through immediate backend service queries. Such synchronization eliminates excessive "hard waits," ensures comprehensive data integrity, and enhances the overall execution speed of the test suite. This methodology is particularly effective for enterprise-grade systems where desktop clients function as frontends for complex distributed infrastructures. Keywords: hybrid Validation, Desktop Automation, Appium, WinAppDriver, REST API, C#, Data Integrity, E2E Testing, Test Synchronization.