bookmark JET2 Viewer A database of predicted multiple, possibly overlapping, protein-protein interaction (PPI). JET2 Viewer reports putative protein binding sites for all three-dimensional (3D) structures available in the Protein Data Bank (PDB). This knowledge base was generated by applying the computational method JET2 at large-scale on more than 20,000 chains. JET2 strategy yields very precise predictions of interacting surfaces and unravels their evolutionary process and complexity. JET2 Viewer provides an online intelligent display, including interactive 3D visualization of the binding sites mapped onto PDB structures and suitable files recording JET2 analyses. Predictions were evaluated on more than 15,000 experimentally characterized protein interfaces. The data can be used to foster new strategies for PPI modulation and interaction surface redesign.