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All of it begins with Ethereum. The L1 is simply too gradual. Each node must redundantly re-execute transactions in a block to make sure validity, which limits scalability.
By 2020, the Ethereum neighborhood coalesced round rollups as the scaling answer. Vitalik’s 2021 landmark weblog submit on rollups explains how optimistic and zk rollups can scale Ethereum.
Zk rollups are technologically superior for scaling however the tech was nonetheless too costly to make use of and much behind (extra later).
So optimistic rollups broke into the market first. Optimistic rollups assume all transactions are legitimate till somebody challenges it with a fraud proof inside a seven-day problem interval.
Optimistic rollups labored, however they got here with hidden prices. The problem interval meant longer transaction finality earlier than customers may withdraw funds. Locked liquidity meant capital efficiencies and a usually poorer UX, particularly with chain interoperability.
In the meantime, zk was catching up. At ETHCC 2022, Polygon, zkSync and Scroll all introduced zkEVMs, which allow Solidity devs to put in writing code and show the execution of the EVM — successfully permitting Ethereum to leverage zero data expertise.
By 2023, zk rollups began to achieve actual traction.
Why precisely are zk proofs higher than optimistic fraud proofs? Particularly as a result of zk proofs are a lot smaller (~1-10 KB) in comparison with uncooked transaction knowledge (megabytes in dimension).
By utilizing zk cryptography to show Ethereum transactions, these extremely compressed proofs meant decrease knowledge availability prices and higher scalability.
How zero data works in a nutshell
Although zk was taking off, proof technology was nonetheless costly. Primarily based on zkstats.io, the typical price to generate a zk proof in December 2023 was $80.21.
Quick ahead to 2025. Proof prices have dropped to $1.3 per proof, a couple of 98.4% enchancment.
What modified?
In the present day, every of the core items of the zk rollup stack have been damaged up.
Firstly, zkVMs are right here. These specialised digital machines velocity up the zk growth expertise and make validity proof technology extra environment friendly. Earlier than zkVMs, builders wanted to put in writing complicated, mathematical “circuits” to show EVM execution.
ZkVMs like SP1, RISC Zero, Nexus and OpenVM at this time successfully democratize zk growth for all builders (C++, Rust) with out zk cryptographic experience. Up to now, zkEVMs solely enabled Solidity growth on zk rollups. Consider zkVMs as a extra normal idea than zkEVMs.
Second, the prices to generate proofs are taking place due to market competitors. In the present day, there are numerous aggressive marketplaces operated by Risc Zero, Cysic, Lagrange and Succinct. Some are nonetheless in testnet, some are operational.
Zk L2s are additionally turning to proof aggregation methods to amortize verification prices. The best way this roughly works is by batching many proofs inside of 1, which makes the ultimate proof sooner to confirm.
These marketplaces are additionally permissionless, which means anybody with a GPU rig can join, submit a bond and generate zk proofs. Beforehand, zk rollups used “centralized provers,” which means they rented GPU/FPGA {hardware} from Google or Amazon.
Higher proof techniques are additionally continually launching. These proof techniques (examples: Groth16, Halo2-KZG, STARK, Plonk, Expander) algorithmically outline the foundations as to how zk proofs are constructed and verified. They’re getting higher, which suggests zk proofs are getting smaller and sooner to confirm. This in flip means elevated zkVM efficiency positive factors.
