Citizen portals are the digital face of modern government, aggregating various online services under a unified interface. They offer features such as secure login via national eID systems, application submission, document upload, and status tracking. Best-practice examples in Europe include Estonia's eesti.ee, Austria's oesterreich.gv.at, and the UK's GOV.UK. Key success factors include intuitive design, accessibility compliance, and mobile-first development, as a large share of users access services via smartphones. Privacy-compliant single sign-on reduces barriers and increases adoption rates. In Germany, the OZG portal federation aims to interconnect federal, state, and municipal portals into a coherent user experience.