There is a new version for this service, check it here. The Frustratometer is an Energy Landscape Theory inspired algorithm that aims at quantifying the degree of local frustration manifested in protein molecules. Frustration is a useful concept for gaining insight to the proteins biological behavior by analyzing how the energy is distributed in protein structures and how mutations or conformational changes shift the energy distributions. Sites of high local frustration often indicate biologically important regions such as binding or allosteric sites. Minimally frustrated linkages constitute a stable folding core of the molecule.