This contribution explores a particular aspect of the protection of fundamental rights in the Internet: the horizontal application of fundamental rights to online platforms. Internet platforms are increasingly required to enforce fundamental rights online by often assuming the task of balancing competing rights. As a result, Internet platforms become adjudicators of fundamental rights online with quasi-judicial powers. This paper attempts to propose a systematic method for assessing the appropriate framework under which the balancing of fundamental rights by Internet private entities should take place. Drawing upon the literature on digital constitutionalism, it argues that such a method requires an assessment of i) the architecture that is created by the horizontal effects of fundamental rights online; ii) the content and context of the removal request as well as the relevant processes; and, iii) the diverse rights and interests at stake.