Lachesis (Fantom Consensus)

Lachesis is the consensus mechanism developed by the Fantom Foundation for its Opera network, which launched in 2019. It is described as asynchronous Byzantine fault tolerant (aBFT), meaning it is designed to reach agreement even if messages are delayed unpredictably and up to a third of validators are faulty or dishonest. Instead of a single leader proposing each block, every validator creates "events" that reference earlier events from others, forming a directed acyclic graph. Validators then work out the same final order from that graph, giving fast, final confirmation rather than probabilistic finality. The approach is related to hashgraph-style designs. Validators are chosen by staking FTM. Fantom rebranded as Sonic, with a new network and token, during 2024 and 2025.