Pytools4dart is a Python API for DART radiative transfer simulator. This python package was developed to address scripted simulations, especially for simulations with dimensions, number of parameters or complexity not manageable with DART graphical interface. Typical examples are the production of a 3D mockups with thousands of voxels or objects and thousands of optical properties (e.g. voxelised lidar data intersected with crown specific bio-chemical traits), or the specification of hundreds of spectral bands to simulate a hyperspectral sensor. Package Pytools4dart extends DART to complex and massive simulation with the power of python for pre/post processing and analysis, by making possible the connection to any other python packages (rasterio, laspy, scikitlearn, ...). It also extends DART to computing on headless server, typically HPC servers. And with python scripting, it allows for easy lightweight version control, e.g. with git, to keep track of your simulation history.