Collaborative economy includes different business models which have in common the use of internet, new technologies and online sharing platforms that intermediate between demand and supply of services and goods for temporary use. Despite of their many benefits, concerns and risks can also be detected, which mostly arise from the lack of clarity about their legal nature and the applicable law. Therefore, the thesis first presents the definitions of the collaborative economy and the relevant sources of law. The guidelines of the European Commission and the case law from the EU Court of Justice are contributing to greater legal clarity on the application of existing rules. Furthermore, the thesis discusses the possibilities of future legal regulation and whether this business models require a special regulation. It is necessary to take into account the online platform's ability of self-regulation and negative effects of ex ante regulation of this evolving field. At the same time, at least a minimum regulation is needed to give platforms access to the market where there are unnecessary regulatory barriers and to ensure minimum safety standards as well as eliminating perceived abuses. The last part of the thesis addresses the issues concerning competition law as one of the legal areas where violations have been alleged and where specific features of online platforms raise concerns about the appropriateness of existing regulation. When analysing prohibited agreements and concerted practices, abuse of a dominant position, unfair competition and state aids, we need to take into account characteristics such as use of computerized algorithms for automatic decision-making, network effects and the associated possibility of rapidly gaining market power, as they change the ways of understanding this areas of competition law.