The functional description of EWEB, a tool for automatic empirical evaluation of web navigation, is presented in this document. EWEB supports naïve evaluators for designing experiments which contain experiment type (within-subject, factorial, etc.), web logs to be captured (time, visited pages, etc.), task models (search task, free navigation) and surveys (questionnaires, card sorting) to be performed by experimental participants. EWEB stores navigational data preserving the experiment structure and supports data analysis and interpretation, with the possibility of generating usability metrics. Requiring minimal installation on client computer, EWEB can be used for both lab evaluation and remote evaluation in multiple browsers. One empirical web study, designed and performed by means of EWEB, is described in order to illustrate its validity as a research tool.