SPRAY-WEB is the research-version of the Lagrangian particle model SPRAY. A consortium has been established and the partners consider of general utility that the model SPRAY could be made available to a wider researcher community, which contributes to its development, update and to a more disseminated use for environmental problems. SPRAY-WEB is particularly suitable for studying the atmospheric pollution processes under complex meteorological and orographic conditions (typical of the Italian regions), avoiding the impact assessment errors obtained by more simplified models, which are not able to reproduce the dispersion under non-stationary and non-uniform conditions. The model can then be effectively used both in the impact assessment of plants and infrastructures and in the analysis of very severe configurations in terms of air quality alteration (e.g., urban centres, industrial sites, ...). The complexity of the atmospheric dispersion makes necessary the continuous improvement of the algorithms implemented. The partners  (called "developers") are responsible for intervening and maintaining the code;  they have personnel suitable for orienting and verifying the developments which might be useful and necessary. SPRAY-WEB site is at http://sprayweb.isac.cnr.it/