In the Kolflow project, our general objective is to develop an assistance engine suitable for distributed applications. In order to provide contextualized and relevant assistance, we feed the assistance engine with interaction traces. Interaction traces record events occurring while users are interacting with applications. These traces become containers of valuable knowledge to providing assistance. Collecting interaction traces is a challenging issue that has been thoroughly studied in the context of local applications. In contrast , few approaches focus on collecting interaction traces in distributed applications. Yet, when applications are distributed , collecting interaction traces is even more challenging because new difficulties arise, such as data synchronization and multi-synchronous collaboration. In this paper, we propose a model and a tool for collecting traces in a distributed environment. The originality of the model is that it is tailored to fit distributed applications. We implemented the model in Collectra, a tool to collect interaction traces in distributed web applications. Collectra collects interaction traces and stores them in a dedicated trace-base management system. We report on the experiments we have conducted in order to evaluate performances of Collectra (both response time and memory space). Results of the experiments show that Collectra performs well and that it can be used to support the assistance tasks carried out by the assistance engine.