ANVIL is aimed at assigning membrane boundaries to a protein 3D structure, by using the spatial coordinates of the alpha carbons. It can also process coarse- grained models of protein structures. The algorithm follows an approach that treats the problem of membrane assignment as a binary classification. The software is implemented in Python and intended to be run with the PyPy interpreter. In output, ANVIL writes a PDB file that contains the coordinates of the membrane, which can be visualized with softwares, such as RasMol or PyMOL. The ANVIL source code is freely available under a CeCILL License.