This workshop introduces the Binaural Rendering Toolbox (BRT), a set of open-source (GPLv3) software libraries, applications, and definitions aimed as a virtual laboratory for spatial psychoacoustic experimentation. The BRT provides a flexible and modular framework for binaural spatialisation, supporting multiple rendering models, including convolution-based and geometric approaches, as well as advanced features such as source directivity, several room acoustics models, individual HRTFs, BRIRs, near-field simulation, and real-time control via OSC.