Estimates of evapotranspiration (ET) which can be derived from in-situ measurements are often difficult to compare because they originate from different research disciplines, were collected at different scales using a range of methods, and they entail method-specific uncertainties.The BRIDGET toolbox – developed within the Digital Earth project – aims to support the harmonisation and scaling of diverse in-situ ET measurements by providing tools for storage, merging and visualisation of multi-scale and multi-sensor ET data. This requires an appropriate metadata description for the various measurements as well as an assessment of method-specific uncertainties.BRIDGET is implemented both as a standalone Python package and as part of the existing virtual research environment V-FOR-WaTer. It is organised as a toolbox consisting of several sub-sections which deal with the different in-situ measurement methods, their typical scaling approaches and most relevant analysis functions. A corresponding uncertainty framework is developed separately as a Python package and as a tool in V-FOR-WaTer. Our first focus for BRIDGET is upscaling tree-level sap flow measurements and comparing them to respective transpiration estimates from eddy covariance and lysimeters.