Scroll zkEVM batch compression and calldata cost reduction
Scroll's October 2026 upgrade achieves a 10x reduction in calldata costs through advanced batch compression. This mechanism utilizes zero-knowledge proofs to minimize data requirements on Ethereum, helping to lower transaction fees for all network participants.
The October 2026 upgrade reduces calldata costs for Scroll by 10x. This change affects how the network performs batch compression. Rollups bundle many off-chain transactions into a single submission for the main chain. Because Scroll is a zkRollup, it uses zero-knowledge proofs to confirm the validity of every transaction in a batch, which reduces the data each transaction adds to Layer 1 and lowers fees. This mechanism makes the base layer a settlement and data-availability anchor. The cost of one Ethereum transaction is shared across many rollup transactions. EIP-4844 introduced blob transactions to provide a cheaper data lane for rollups using 128 KB temporary data chunks. These blobs are stored on Ethereum’s consensus layer for about 18 days before they are pruned. EIP-7623 also adjusted the calldata cost floor to a balanced level for the network. This adjustment helps preserve the health of the network while providing flexibility for high-data users. The blockchain trilemma describes the difficulty of achieving security, decentralization, and scalability at the same time. Most networks prioritize two of these properties, which can limit the third. Layer 2 solutions build on top of a Layer 1 to handle more transactions off the main chain, reducing congestion and fees. Rollups have become the primary scaling method for Ethereum. Most blockchain ecosystems move toward a combination of Layer 1 improvements for long-term security and Layer 2 networks for everyday speed and affordability.
The technical execution of Scroll
The sequencer orders transactions before they reach the mainnet. The prover then generates the zero-knowledge proofs that verify the batch. This process ensures that the state transition is correct without requiring the mainnet to re-execute every transaction. Scroll uses a zkEVM to maintain compatibility with Ethereum. The network aggregates transactions into a single proof to minimize gas fees for all participants. You might find that the separation of execution and settlement changes how you view transaction finality. The transaction lifecycle follows three specific phases. First, users submit a transaction to the sequencer, which confirms the action within three seconds. Second, the network includes these transactions in a batch that is submitted to the mainnet, typically within minutes. Third, the validity proof is generated and verified on the mainnet, which finalizes the batch.
| Phase | Duration |
|---|---|
| Confirmed | 3 seconds |
| Committed | Minutes |
| Finalized | Tens of minutes |
The prover uses the Halo2 proving system to generate these proofs. Scroll is a Type 3 zkEVM.
Efficiency and network performance
The reduction in calldata prices affects the cost of data availability. In many ZK systems, the network stores state-diffs instead of full transactions to save space. This method requires fewer bytes for the data availability layer. While the upgrade lowers costs, Scroll is slower than Starknet in both transaction per second (TPS) and finality speed. By reducing the amount of data required for each batch through advanced compression, the network allows more users to participate without the prohibitive costs typically associated with high congestion on the Ethereum mainnet. Optimistic rollups like Arbitrum or Base assume transactions are valid unless a challenger submits a fraud proof. This allows for a challenge period of seven days. ZK rollups like Scroll or zkSync use validity proofs to demonstrate correctness, which allows for faster withdrawals. ZK-SNARKs are tiny and fast to verify, making them practical for on-chain verification. In contrast, ZK-STARKs avoid a trusted setup but have larger proof sizes. Transaction fees on L2s average around $0.08 compared to $3.78 on Ethereum mainnet as of Q1 2025. A DeFi swap costs roughly $0.03 on Arbitrum versus several dollars on mainnet. Because ZK rollups use validity proofs, they do not need to wait for a challenge window to end before the state is considered final. This enables users to move assets back to Layer 1 more quickly. Rollups bundle transactions by submitting a compressed batch of data to the main chain, which spreads the fixed gas costs of a transaction among many participants. Will the reduction in calldata costs lead to a permanent shift in how developers design zero-knowledge applications?
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