Rollup Wars: Battle Rages For the Future Of Ethereum Scaling

Offchain Labs Co-founder Takes Aim At Zero-Knowledge Technology

By: Samuel Haig Loading...

Rollup Wars: Battle Rages For the Future Of Ethereum Scaling

Some of Ethereum’s top Layer 2 teams are fiercely debating whether optimistic or zero-knowledge rollups will triumph as the network’s leading scaling solution.

On Jan. 29, Steven Goldfeder, the co-founder of Offchain Labs, the team behind leading optimistic rollup, Arbitrum, took aim at what he describes as a commonly held belief that ZK-rollups will emerge as Ethereum’s dominant scaling solution once the technology becomes widely available.

“There’s a narrative out there that ZK Rollups will be able to do everything that Optimistic Rollups do but better,” Goldfeder tweeted. “Let me tell you why I’m still bullish on Arbitrum’s technology winning.”

Rollups reduce transaction fees by bundling together transactions on Layer 2 and then submitting them to the Ethereum mainnet in batches for finalization.

Arbitrum and Optimism, two optimistic rollups, are currently the leading L2 networks, boasting 51% and 31% of the sector’s total value locked, respectively, according to L2beat.

Optimistic Rollups

These rollups work by optimistically assuming that all mainnet transactions submitted by validators are honest and accurate, but withdrawals to mainnet have a seven-day delay to allow for fraud to be detected. Validators must post significant collateral, which can be slashed if they submit fraudulent transactions.

ZK Rollups

By contrast, rollups based on zero-knowledge proofs promise to do away with the seven-day delay on mainnet withdrawals while offering faster transactions with greater privacy protections.

However, existing ZK-based solutions do not offer compatibility with the Ethereum Virtual Machine, Ethereum’s core smart contract engine, meaning that developers cannot easily port their code from Ethereum to currently deployed ZK rollups.

EVM Compatibility

Goldfeder also derided the fact there are no ZK-rollups offering EVM compatibility currently available for public use. “For the past few years, we’ve been perpetually told that it’s 3-6 months away, but that never seems to get shorter,” he said.

Polygon, Matter Labs, Scroll, and blockchain software heavyweight Consensys, are among the teams currently working on Ethereum-compatible ZK-rollups. While early testnets are live for each of their respective zkEVM offerings, Matter Labs and Polygon expect to launch their mainnets by the second half of 2023.

The Offchain Labs co-founder also asserted that optimistic rollups can support non-EVM contracts within the same execution environment supporting EVM transactions.


“There’s lots that we can do to supplement the EVM (EVM+) to make Arbitrum more inclusive and welcoming to a wider set of developers and users,” Goldfeder said. “ZK teams are doing a ton of complex engineering to target EVM, and many of the decisions they’re making today will make adding these EVM+ features nearly impossible.”

While the thread garnered some support on social media, many Twitter users responded to Goldfeder’s comments by defending ZK solutions or criticizing optimistic rollups.

Hkm.eth, a crypto investor, believes Arbitrum currently enjoys a dominant share of the L2 market due to its early-mover advantage relative to ZK solutions. “The day we see more mature implementations of ZK rollups and ZKevms, Optimistic rollups can lose their market share,” they tweeted.

“The first iterations of ZK are not going to have nearly the level of polish that the current batch of [optimistic rollups] have,” opined Pikag.eth. “Just like Arbitrum, [ZK rollups] will start in beta.”

Brendan Farmer, a core contributor to Mir, a zero-knowledge scaling solution acquired by Polygon in a $400M deal that closed in Dec 2021, replied to Goldfeder that “the best way to scale Ethereum is with ZK, not optimistic rollups.”

Lower Transaction Fees

“Proving costs for the 0xPolygon zkEVM are already tiny — $0.0019 for a Uniswap trade,” Farmer said.

Farmer also noted that the testnet for Polygon’s zkEVM has already produced 80,000 block proofs and is on track for a mainnet deployment in less than three months.

Correction: Corrects headline to report Offchain Labs co-founder takes aim at zero-knowledge technology, not Matter Labs.