With the advent of wearable sensing and mobile technologies,
biosignals have seen an increasingly growing number of application
areas, leading to the collection of large volumes of data. One of the
difficulties in dealing with these data sets, and in the development
of automated machine learning systems which use them as input, is the
lack of reliable ground truth information. In this paper we present a new web-based platform for visualization, retrieval and annotations of biosignals by non-technical users, aimed at improving the process of ground truth collection for biomedical applications. Moreover, a novel extendable and scalable data representation model and persistency framework is presented. The results of the experimental evaluation with possible users has further confirmed the potential of the presented framework.