This is the Simulating Annealing Network Aligner, designed originally to align protein-protein interaction (PPI) networks, but now is able to align arbitrary undirected graphs, weighted on unweighted. It can produce near-optimal alignments of PPI-sized networks in about an hour, and it has been used to successfully align networks with up to 100,000 nodes and 100 million edges (though those alignments take about a week of CPU to complete).
For details, consult our original paper: https://doi.org/10.1093/bioinformatics/btx090 A tutorial intrdocution is available at https://arxiv.org/abs/1911.10133