Anatomy of a Modular Rollup Stack

Execution Layer: EVM, WASM, Custom VMs

Execution environments within modern rollups have diversified significantly beyond traditional Ethereum Virtual Machine (EVM) compatibility. While EVM remains the default for many deployments due to familiarity and tooling support, new frameworks increasingly offer WASM‑based virtual machines or hybrid solutions such as zkEVM and custom VMs. These alternatives address EVM limitations by enabling higher throughput, multi‑language support, or optimized cryptographic proof systems. For example, some implementations now deliver blended EVM+WASM environments, allowing developers to write contracts in Solidity or Rust while benefiting from advanced execution models and performance gains.

Innovations like DTVM introduce deterministic virtual machine architectures that achieve significantly faster contract execution, compatibility with multiple ISA (Instruction Set Architectures), and deterministic JIT compilation pipelines. These hybrid designs typically outperform EVM-only chains by twofold in execution speed while preserving ABI compatibility with Ethereum tooling.

Sequencers: Centralized, Decentralized, and Shared Models

Sequencers play a pivotal role in ordering and batching transactions within rollups. The traditional model remains centralized sequencers, which offer high throughput and simplicity but expose rollups to censorship risk and MEV (Miner Extractable Value) concentration. Increasingly, projects pursue decentralization by transitioning toward based rollups, where sequencing authority is gradually delegated to validator sets or proposer networks integrated with L1 protocols.

Shared sequencers represent a third model emerging in 2025, where multiple rollups leverage a single decentralized sequencing network. This setup aims to improve cross‑rollup composability while mitigating the cost and operational burden of each rollup maintaining its own sequencing infrastructure. Projects like Astria or Espresso model shared sequencing networks, and early research has begun quantifying their effects on MEV coordination and arbitrage profitability.

Data Availability (DA) Layers: Celestia, EigenDA, Avail

Data availability layers form a critical foundation in modular rollup systems by decoupling data storage and availability guarantees from execution. Celestia pioneered a modular blockchain offering consensus and DA services without execution logic, employing Data Availability Sampling to allow light clients to verify block data without full downloads. Its design enables high throughput (e.g., multi‑MB blocks per second) and scalability that execution layers cannot achieve on their own.

EigenDA builds atop Ethereum via EigenLayer restaking, inheriting Ethereum security while offering DA as a service. It leverages erasure coding and cryptographic commitments to provide secure, high-throughput DA at much lower cost than posting full data to Ethereum directly. Avail, developed by Polygon, offers a chain-agnostic DA layer optimized for rollups across multiple ecosystems. It separates DA from consensus, supports sampling for light client verification, and aims at interoperability across rollup networks.

Settlement & Bridging: Posting Proofs to L1 Chains

Settlement refers to the process of finalizing a rollup’s state onto a Layer 1 chain. This often involves posting state commitments or proofs back to an L1 such as Ethereum. Optimistic rollups rely on fraud proofs to contest invalid states during a challenge window, while ZK rollups provide cryptographic verification upfront via validity proofs. Either method establishes trust and settlement guarantees at the base layer, which upholds consensus and security independently of rollups operating above it.

Bridging infrastructure connects rollups to user assets and external networks. Bridges must securely move tokens or data across chains and often rely on designs aligned with the rollup’s proof system and DA layer. Settlement integrates tightly with bridging protocols, so transfers registered on the rollup can be recognized and finalized on the target chain. These connections leverage both on-chain contracts and off-chain infrastructure to maintain trust and continuity.

Security Models: Fraud Proofs, Validity Proofs, Restaked Security

Security in modular rollups hinges on proof systems and settlement layering. Optimistic rollups depend on fraud proofs, where participants challenge incorrect state transitions within a designated window. This ensures that invalid transactions may be reverted before finality. ZK rollups, by contrast, submit validity proofs that cryptographically guarantee correctness before inclusion, resulting in near-instant finality and resistance to state manipulation.

In addition to proof types, some rollups adopt restaked security models via EigenLayer’s Actively Validated Services (AVSs). These systems allow validator sets to restake assets on Ethereum and extend security guarantees to DA layers and execution environments. This design enables modular security guarantees to scale with Ethereum’s trust assumptions while maintaining flexibility in rollup deployment and upgradeability. By selecting appropriate combinations of proof systems, DA providers, and validator staking models, teams assembling a modular rollup stack can tailor trade-offs between finality speed, decentralization, trust assumptions, and cost.