The Mangrove is an order book-based DEX that allows liquidity providers to post arbitrary smart contracts as offers. This new flexibility enables liquidity providers to post offers that are not fully provisioned. The Mangrove's order book lists promises instead of locked commitments. Liquidity can be shared, borrowed, lent and, at the same time, be displayed in the Mangrove's order book, ready to be sourced when, and only when, an offer is hit. The time of DeFi 's fragmentation in a myriad of pools is ending. In the Mangrove, liquidity reaches its ultimate potential. Value doesn't have to be locked anymore.