webXTREME: R-based web tool for calculating agroclimatic indices of extreme events

•A new web-based tool for the evaluation of agroclimatic indices.•Simple implementation using Shiny and the R Statistical Language.•Targets extreme temperature and aridity.•Global access and applicability.•Suitable for risk assessment under climate change.

We document the release of webXTREME, a new online tool for the evaluation of indices of climatic extremes (extreme temperatures and aridity) having impact on agricultural production. The tool is globally available and can be operated with either observed weather data or time series representing future climatic conditions. It is thus suitable for risk evaluation under climate change. webXTREME was implemented using Shiny, an open-source programming framework for creating web applications on the basis of the R Statistical Language.