The INSPIRE Directive was established by the European Union to improve the sharing and interoperability of spatial data across member states, to promote consistent environmental policies and spatial data infrastructures. Despite its aims, challenges remain in harmonising and uniting data formats, metadata quality, and service availability, leading to inconsistency in data sharing practices. This thesis examines the current state of INSPIRE implementation across six EU countries: Sweden, Germany, Spain, Croatia, Romania, and Malta. A comparative analysis is conducted, focusing on metadata quality, service availability, and spatial data completeness. The methodology includes systematic assessments using the INSPIRE Reference Validator and a custom Python script to look at the countries and compare them. Key findings reveal significant differences in compatibility across the six countries. Spain scored highest overall, showing strong metadata and accessibility, while Sweden and Germany despite their policy level alignment struggled with metadata conformity and access restrictions. All countries failed in dataset completeness for certain themes, such as Hydrography and Protected Sites. These gaps show that even well aligned countries face problems in practice. The study identifies metadata quality, service accessibility, and dataset completeness as key indicators for measuring compatibility, and shows that failure in any one of them limits the overall usability of spatial data. While progress with compatibility has already been made, substantial work remains to achieve INSPIRE’s vision of seamless cross-border data interoperability. This study will identify challenges and suggest recommendations to enhance the implementation of INSPIRE guidelines.