HADDOCK is a versatile information-driven flexible docking approach for the modelling of biomolecular complexes. HADDOCK distinguishes itself from ab-initio docking methods in the fact that it can integrate information derived from biochemical, biophysical or bioinformatics methods to enhance sampling, scoring, or both. The information that can be integrated is quite diverse: interface restraints from NMR or MS, mutagenesis experiments, or bioinformatics predictions; various orientational restraints from NMR and, recently, cryo-electron maps. Currently, HADDOCK allows the modelling of large assemblies consisting of up to 6 different molecules, which together with its rich data support, provides a truly integrative modelling platform.