We propose a technique to collect use traces in any existing applica-tion, without a need to modify this application. This technique is based on the use of accessibility libraries. We implemented our technique in a collector that uses UIAutomation and JavaAccessibility libraries: it can monitor Windows target-applications to collect the user’s traces. The traces are then stored in a trace-base management system in order to be exploited thereafter. We have tested our collector on more than fifty applications in order to evaluate our ap-proach.