MercuryWallet
Mercury is a new Bitcoin layer-2 scaling technology, based on the concept of statechains, that enables private keys for BTC deposits (UTXOs) to be transfered securely between owners without requiring an on-chain transaction.
This enables users to transfer full custody of an amount of BTC to anyone almost instantly, with increased privacy, and without having to pay miner fees. Mercury also supports the first production CoinSwap implementation.