Why Shared Sequencers Will Redefine L2 Interoperability

Today's bridges are slow, risky, and expensive because they operate on finalized blocks. A shared sequencer enables atomic composability across L2s by ordering transactions into a single, shared block before execution.\n- Eliminates MEV from cross-chain arbitrage by batching intents.\n- Unlocks native cross-rollup DeFi with sub-second latency.\n- Turns L2s into parallel execution shards of a unified state machine.

Every independent rollup sequencer is a multi-billion dollar honeypot requiring its own costly trust assumptions and validator set. A decentralized shared sequencer, like Espresso Systems or Astria, aggregates security.\n- Dilutes cost of decentralized sequencing across all participating chains.\n- Enables credibly neutral, Ethereum-aligned ordering resistant to capture.\n- Creates a unified liveness assumption, mitigating individual chain halts.

Fragmented liquidity across Arbitrum, Optimism, and zkSync cripples capital efficiency and UX. A shared sequencer network creates a synchronous cross-rollup environment, making liquidity programmatically accessible anywhere.\n- Enables intent-based routing (like UniswapX) across all connected L2s.\n- Dramatically reduces bridging volume and associated costs.\n- Turns every L2 into a liquidity source for every other, creating a unified money market.

Every major L2—Arbitrum, Optimism, Base—runs its own sequencer. This creates vendor lock-in, fragmented liquidity, and forces users to trust a single, centralized operator for transaction ordering and censorship resistance.

• No Atomic Composability: You can't atomically swap assets between Arbitrum and Optimism.
• Centralized Control Point: The sequencer is a single entity that can censor or reorder transactions.
• Fragmented MEV: MEV is captured and siloed within each rollup, limiting efficiency.

Astria provides a shared, decentralized network of sequencer nodes that multiple rollups can plug into. It's rollup-agnostic, offering a neutral ordering service that rollups can permissionlessly adopt.

• Decentralized Validator Set: Uses Celestia for data availability and a Tendermint-based consensus for ordering.
• Fast Finality: Aims for ~1-2 second block times, faster than Ethereum L1.
• Interoperability Primitive: Enables atomic cross-rollup transactions by sharing the sequencing layer.

Espresso Systems builds a configurable shared sequencer powered by HotShot, a high-throughput consensus protocol. It emphasizes decentralization and integration with EigenLayer for cryptoeconomic security.

• EigenLayer Integration: Leverages restaked ETH to secure the sequencer set, avoiding a new token.
• Configurable Finality: Offers both soft (fast) and hard (slow) confirmation for different app needs.
• Timeboost: A fair ordering mechanism to mitigate MEV, similar to ideas from Flashbots.

A mature shared sequencer network doesn't just order transactions—it becomes the central nervous system for modular blockchains. This enables use cases impossible in today's fragmented landscape.

• Atomic Cross-Rollup Swaps: Native, trust-minimized swaps between any connected rollup, rivaling LayerZero and Axelar.
• Shared MEV Auctions: A global marketplace for cross-domain MEV, increasing extractable value.
• Unified User Experience: A single wallet/balance that spans multiple execution environments.

Today's cross-chain swaps are a series of risky, slow, and expensive independent transactions. Users face sovereign risk and MEV extraction at every hop.\n- No native atomic execution across L2s\n- ~$100M+ lost to bridge hacks in 2023\n- 30+ minute settlement delays for complex routes

A shared sequencer acts as a single, neutral ordering service for multiple rollups, creating a shared mempool and atomic block space.\n- Enables cross-rollup atomic composability (like UniswapX on steroids)\n- Reduces finality time from minutes to ~500ms for cross-L2 txs\n- Unlocks new primitives like shared liquidity and cross-domain MEV capture

Espresso's HotShot consensus provides the high-throughput, low-latency DA layer that makes shared sequencing viable. It's the technical bedrock for projects like Rollup-as-a-Service providers (e.g., Conduit, Caldera) and L2s (e.g., Arbitrum, Optimism testnets).\n- Decentralized validator set replaces a single sequencer\n- Sub-second finality enables real-time cross-chain apps\n- Data Availability sampling integrated for full-stack scaling

Shared sequencing transforms user experience by enabling intent-based architectures across chains. Users submit a desired outcome (e.g., 'swap ETH for ARB on L2-B'), and solvers compete in the shared mempool to fulfill it atomically.\n- Eliminates bridge UX; feels like a single-chain swap\n- Solvers (like Across, CowSwap) optimize for best execution\n- Unlocks native cross-L2 limit orders and batch auctions

A shared sequencer captures and democratizes cross-domain MEV—value currently leaked to centralized sequencers and bridge validators. This creates a sustainable economic model.\n- MEV proceeds are redistributed to participating rollups and their stakers\n- Creates strong economic alignment between L2 ecosystems\n- Incentivizes decentralization of the sequencer set

Shared sequencing is the inevitable infrastructure for aligned L2 ecosystems like the OP Stack Superchain and Arbitrum Orbit. It turns a coalition of chains into a single, coherent hyper-scaled computer.\n- Base, Zora, Mode become atomic execution zones\n- Shared security model reduces bootstrap costs for new chains\n- Final step before full Ethereum-level interoperability via shared sequencing layers like Astria