Heterogeneity of current terminals and networks leads to data transmission disturbances, particularly with multimedia flows. Dynamic adaptation is a de facto solution which enables users to exchange any datatype in an optimal way, in spite of various networks, terminals, applications, needs and preferences. Furthermore, we introduce global adaptation as an innovative approach of adaptating data to various parameters, involved by the multiplicity of users. To achieve global adaptation, we propose a platform called Appat (Adaptation Proxies PlATform) which is described in this paper. Appat is composed of Adaptation Proxies (APs) dedicated to adaptation tasks. It permits to realize dynamic adaptation of transmitted data in a distributed fashion, thus unloading users' terminals from this work. Adaptation and platform management is done by the APs, transparently to connected hosts, which totally make abstraction of these processes.