Development and implementation of the entire warehouse system of BKV in Pascal, Clipper and Clarion.Planning and implementation of the entire IT system of Népszabadság Zrt. (planning, commissioning and later operation of a network containing 350 workstations and 15 servers). Transition from VMS, Novell and DOS bases to Microsoft Windows bases (Windows 95, 98, XP, NT4 and later 2000, 2003). Implementation of a mail system (Exchange Server 5.5, MDaemon, later Exchange 2003). NT4 Domain upgrade to 2003 Active Directory (Windows 2003). Introduction of Internet access (MS Proxy Server then MS ISA Server 2003).Introduction and replacement of the editorial system. (ATEX then WOODWING). Carrying out age-appropriate system development (server virtualization), mobilizing workstations (laptops), introducing SAN and creating the possibility of remote work.After closing the page, operation and development of the entire system of Lighttech Kft., migration from VMWare 5.5 to 7, HA PfSense firewall, Microsoft Exchange 2013, Microsoft SQL 2016, Linux (Debian, Ubuntu), Raspberry Pi-based IoT company management support system. Later, my duties were expanded by performing the administrative duties of the Sauska wineries and Light-Sources Inc in Connecticut, and from the end of 2019 I also performed the IT management duties.From 2021, I continued my work at Poli Computer Pc Kft. Here, as an external expert, I performed system operator activities related to the operation of Windows infrastructure for the NISZ and the NKH.