There is a specification of the protocol, which is open source: https://github.com/ethereum/consensus-specs https://github.com/ethereum/consensus-specs And the

There is a specification of the protocol, which is open source: https://github.com/ethereum/consensus-specs https://github.com/ethereum/consensus-specs And there are over 5 interoperable, independent and open source implementations of said specification: - https://github.com/sigp/lighthouse/ https://github.com/sigp/lighthouse/ - https://github.com/ChainSafe/lodestar https://github.com/ChainSafe/lodestar - https://github.com/status-im/nimbus-eth2 https://github.com/status-im/nimbus-eth2 - https://github.com/prysmaticlabs/prysm https://github.com/prysmaticlabs/prysm - https://github.com/ConsenSys/teku https://github.com/ConsenSys/teku - https://github.com/sifraitech/grandine https://github.com/sifraitech/grandine ...