Copernicus Climate Change Service has developed a new standardised interface to a huge wealth of homogenised and quality controlled climate data: the Climate Data Store (https://www.ecmwf.int/en/newsletter/151/meteorology/climate-service-develops-user-friendly-data-store). Alongside the innovative data infrastructure the system comes with an online platform to develop analysis procedures, value-added products and services to address the needs of specific end-users. This session wants to be a hands-on training on this new cutting-edge system for writing your own tool to select, post-process and visualise climate related variables. The workshop will build upon the free and open datasets currently available (the C3S portfolio includes ECMWF reanalysis, C3S multi-model seasonal predictions system, high-resolution gridded observations, CMIP5 and EURO-CORDEX data..), the python tools developed by ECMWF sub-contractors and the Proof-Of-Concept prototype developed by the Sectoral Information System (https://climate.copernicus.eu/sectoral-information-system). The workshop is targeted to the tech-savvy climate scientist who is interested in learning how to use the Climate Data Store to develop new applications.