Aztec or zk.money, a Layer-2 roll-up, claims to make transactions not only private but also cheaper.

If I send 1 eth on L1 mainnet, all I pay is one gas txn to send it.

If I instead use Aztec's privacy layer, however, I pay the gas txn to transfer the 1 eth to Aztec's network, and then pay a 2nd gas txn to Aztec's smart contract to send the 1 eth to the real address of the recipient. That's 2 gas txns more than sending on L1 mainnet! How can that possibly be cheaper?

1 Answer 1


Transactions from L1 to Aztec are not cheaper - you have to pay the regular L1 transaction fees.

Aztec uses zk-rollup technology. On top of that, they use real ZK (which they tend to call zk-zk-rollup) so they include privacy. Rollups basically gather multiple transactions, generate proofs for them and only post the proofs to L1. Posting these proofs is a lot cheaper than posting the actual transactions.

Because of rollups, transactions inside Aztec are cheap. Furthermore, they use special Bridges which can post regular L1-transaction-type transaction to L1 cheaply. If for example two L2 users want to deposit 1 Eth to a certain L1 protocol, the Bridge only sends 1 transaction to the L1 protocol and the L2 users are distinguished only at the L2 bridge.

  • Ok, so cheaper in the sense that it bundles multiple senders who are sending to the same destination, but not cheaper in the case of one person simply sending money to grandma for privacy, given the 2nd step of re-sending from within the Aztec wallet.
    – user610620
    Commented Dec 9, 2022 at 5:53
  • Yeah, not cheaper if you use Aztec only once. Commented Dec 9, 2022 at 5:59
  • What is the difference between Aztec and ZkSync 2.0? And which other privacy roll-up is Aztec's direct competitor?
    – user610620
    Commented Dec 9, 2022 at 6:08
  • 1
    I'm not aware of other privacy L2s. Aleo is similar, but it's L1. ZkSync is not privacy - they only utilize zk technology for their rollups but don't give you perfect privacy. Commented Dec 9, 2022 at 6:12
  • If someone deposits crypto into a yield farm via Aztec, but then Aztec gets shut down by regulators over privacy laws, or you lost your Aztec private key somehow, can you get your crypto out of the yield farm via Layer-1, even though you went into farming via Layer-2?
    – user610620
    Commented Dec 9, 2022 at 6:17

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