This volume contains papers from the main track of the 13th ITAT conference, which took place on September 11-15, 2013 at Donovaly, Slovakia. ITAT is a computer science conference with the primary goal of presenting new results of young researchers and doctoral students from Slovakia and Czech Republic. The conference serves as a platform for exchange of information within the community, and also provides opportunities for informal meetings of the participants in a mountainous regions of Czech Republic and Slovakia. The traditional topics of the conference include software engineering, data processing and knowledge representation, information security, theoretical foundations of computer science, computational intelligence, distributed computing, natural language processing, and computer science education. The conference accepts papers describing original previously unpublished results, significant work-in-progress reports, as well as reviews of special topics of interest to the conference audience.