Loopring is an open protocol for building high-performance, order book decentralized exchanges on Ethereum. Their goal is to enable the building of highly scalable exchanges without compromising Ethereum-level security guarantees through a zkRollup construction.
Loopring's primary objectives include reducing user reliance on centralized exchanges or other trusted third parties and enabling global liquid markets. Loopring protocol pursues this by incentivizing ecosystem participants to perform exchange functions in a decentralized manner, with trades processed by non-custodial smart contracts.
Although blockchains inherently provide trustless trading, there are problems with building exchanges purely on-chain. Specifically, processing speed, throughput, and computation costs. Performing all exchange steps on-chain can be prohibitively expensive, or impossible to emulate centralized exchange speed and performance. For these reasons, Loopring has moved almost all data and computation off-chain but leverages zero-knowledge proofs to retain trust-minimized properties.
Loopring originally planned to be blockchain agnostic and to operate on all feasible large public blockchains with smart contract capability. Loopring was first deployed on Ethereum to trade ERC20 tokens and uses its LRC token to operate. It has deployed on top of NEO and airdropped a native LRN, however, that effort is paused. There were plans for a similar launch on top of QTUM with an LRQ token but that was scrapped entirely.