Ethereum ($ETH) is the most popular DeFi platform but the flippening could be near with Bitcoin ($BTC)-based DeFi according to Mohamed Fouda. Bitcoin DeFi lending is broken into four areas: current Bitcoin features, federated sidechains, interoperable platforms, and Layer 2 systems. Current Bitcoin features include typical P2P lending and the development of DEX lending. Federated sidechains and interoperable platforms like Blockstream's Liquid and Cosmos ($ATOM) respectively are bridges purposed DeFi systems with Bitcoin often used as the native currency. Layer 2 options like Lightning or Omni Layer are newer non-custodial DeFi options still being explored. With the possible addition of the MAST BIP, Bitcoin's DeFi dreams could be right around the corner.
