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Layer-2 scaling solutions were proposed to help solve the prevalent scalability problem and increase the throughput of the underlying Layer-1 platforms. The current market state of the L2 solutions is very fragmented, but they all differ in terms of their technology and approach. Some of the notable projects using ZK-rollups include Loopring, Aztec 2.0, Matter Labs zkSync, Starkware. In Validium, the data is stored off-chain, which increases transaction throughput and efficiency.