The Internet of Things (IoT) has emerged as a paradigm in which smart things actively collaborate among them and with other physical and virtual objects available in the Web in order to perform high-level tasks. IoT environments are typically characterized by a high degree of heterogeneity, thus encompassing devices with different capabilities, functionalities, and network protocols. In such a scenario, it is necessary to provide abstractions for physical devices and services to applications and end-users, as well as means to manage the interoperability between such heterogeneous elements. In this context, we introduce EcoDiF (Web Ecosystem of Physical Devices), a Web-based platform for integrating heterogeneous physical devices with applications and users in order to provide services to support real-time data control, visualization, processing, and storage. In this paper, we present the main features of EcoDiF and detail its architecture and implementation, which is based on well-known Web technologies such as HTTP, REST, EEML, and EMML. Furthermore, we present a preliminary evaluation of an EcoDiF prototype through proof-of-concept applications from different domains as well as a performance analysis of the platform.