The completion of Ethereum’s Cancun upgrade has significantly reduced L2 gas fees, refocusing market attention on Layer 2 (L2) scaling solutions. Among the dominant L2 approaches today are Optimistic Rollups and ZK Rollups, both designed to scale Ethereum by processing transactions off-chain while posting data back to Layer 1 (L1). While Optimistic Rollups currently dominate in market adoption, both models face inherent limitations in efficiency, cost, and decentralization.
To address these challenges, a novel architectural paradigm—Based Rollup—has emerged. This innovative design simplifies technical complexity, reduces transaction latency, and crucially, is the only Rollup variant that fully inherits Ethereum’s liveness—the guarantee that transactions will eventually be processed even under adversarial conditions. As of now, only a few teams are actively developing Based Rollup solutions, with Taiko leading the charge as a pioneering ZK Rollup team integrating this model.
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The Limitations of Traditional Rollup Models
Optimistic Rollups: Security at the Cost of Speed
Optimistic Rollups operate under the assumption that all transactions are valid by default. To maintain security, they implement a challenge period, typically lasting 7 days, during which fraud proofs can be submitted if malicious activity is detected. While this ensures eventual correctness, it introduces significant delays—especially for fund withdrawals from L2 to L1.
Moreover, during periods of high Ethereum network congestion, submitting fraud proofs can incur substantial gas costs. This reliance on L1 for dispute resolution creates friction and economic inefficiency, undermining the user experience.
ZK Rollups: Efficiency with Computational Overhead
In contrast, ZK Rollups use zero-knowledge proofs to cryptographically verify batches of transactions before anchoring them to Ethereum. This allows near-instant finality and strong data integrity with minimal L1 footprint.
However, generating ZK proofs requires intensive computational resources. The process is time-consuming and expensive, especially for complex smart contract operations. As a result, despite faster confirmation times, ZK Rollups often struggle with high operational costs and limited transactions per second (TPS) scalability due to proof generation bottlenecks.
Both models require complex infrastructure—including dedicated sequencers, consensus mechanisms, data availability layers, and fraud or validity proof systems—leading to increased overhead and potential centralization risks.
Introducing Based Rollup: A Paradigm Shift in L2 Architecture
Proposed by Ethereum researcher Justin Drake in March 2023, the concept of Based Rollup (also known as L1-sequenced Rollup) rethinks how Rollups handle transaction ordering. Unlike traditional Rollups that rely on independent sequencers to order transactions, Based Rollups outsource this responsibility directly to Ethereum’s base layer.
In this model:
- The consensus layer, data availability layer, and settlement layer all reside on Ethereum.
- Only the execution layer operates on the Rollup itself, processing transactions and updating state.
This means Ethereum validators—not external sequencers—are responsible for ordering L2 transactions within L1 blocks. By doing so, Based Rollups eliminate the need for standalone sequencing infrastructure and align their security model completely with Ethereum’s.
It’s important to note that Based Rollup is not an alternative to Optimistic or ZK Rollups but rather a complementary architectural choice. A Rollup can be both a ZK Rollup and a Based Rollup if it uses Ethereum for sequencing. The distinction lies in how sequencing is managed—not in how proofs are validated.
Key Advantages of Based Rollups
✅ Full Inheritance of Ethereum’s Liveness
Based Rollups are the only design that inherits 100% liveness from Ethereum. Since transaction ordering occurs on L1, there's no risk of censorship or sequencing failure—even if the L2 network becomes unresponsive or compromised.
Unlike traditional Rollups that require "escape hatches" (emergency withdrawal mechanisms), which still involve waiting periods and trust assumptions, Based Rollups ensure users can always get their transactions included via Ethereum’s canonical chain.
✅ Simplified Architecture and Enhanced Decentralization
By offloading sequencing to Ethereum, Based Rollups remove the need for:
- Proprietary sequencer nodes
- Escrow mechanisms
- Off-chain consensus protocols (e.g., PoS sidechains)
- Signature verification for sequencer outputs
This drastically reduces system complexity and attack surface, making the network more resilient and easier to audit.
✅ Reduced Latency and Faster Confirmations
With Ethereum handling ordering, confirmations become nearly instantaneous at the protocol level. Users benefit from faster feedback loops, improved UX in DeFi applications, and quicker cross-chain interactions.
✅ Lower Operational Costs
Eliminating dedicated sequencers cuts down on infrastructure expenses. Additionally, batch processing becomes more efficient since ordering is already finalized on L1. These savings compound during high-traffic periods, offering better cost predictability.
✅ Aligned Economic Incentives
Ethereum validators earn additional revenue from including L2 transactions in blocks—effectively capturing MEV (Maximal Extractable Value) from multiple layers. This strengthens their economic incentive to secure the entire stack, promoting long-term ecosystem health and alignment across layers.
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Challenges Facing Based Rollup Adoption
Despite its advantages, Based Rollup technology faces several hurdles:
⚠️ Limited MEV Capture for L2 Projects
Since sequencing occurs on L1, most MEV opportunities flow directly to Ethereum validators. This limits revenue potential for L2 teams that might otherwise monetize advanced ordering strategies or premium transaction services.
⚠️ Reduced Sequencing Flexibility
Outsourcing sequencing may restrict customization. For example, implementing a strict First-Come-First-Served (FCFS) policy—like Arbitrum—requires additional tooling such as EigenLayer restaking to enforce fairness rules on top of Ethereum’s native market-driven inclusion logic.
Additionally, reliance on L1 block timing means less control over real-time transaction prioritization compared to independent sequencers.
Real-World Implementation: Taiko’s Pioneering Approach
Among emerging projects, Taiko stands out as the most advanced implementation of Based Rollup principles. As a ZK Rollup building a Type-1 zkEVM, Taiko replicates Ethereum’s exact execution environment—ensuring full compatibility with existing dApps, tooling, and developer workflows.
Shortly after the Based Rollup concept was introduced, Taiko began integrating L1-based sequencing into its architecture. On January 15, 2025, they launched the Katla testnet, introducing Based Contestable Rollup (BCR)—a hybrid model combining ZK-based validity with contestable fraud-proof-like challenges embedded directly into the validation workflow.
This innovation enables Taiko to maintain high security while benefiting from Ethereum’s liveness guarantees and decentralized sequencing power.
Frequently Asked Questions (FAQ)
Q: What does “inheriting liveness” mean for a Rollup?
A: It means the Rollup guarantees that transactions will eventually be processed and confirmed—even if its own network fails—because it relies on Ethereum’s robust consensus for ordering.
Q: Can Optimistic or ZK Rollups become Based Rollups?
A: Yes. Any Rollup that delegates transaction sequencing to Ethereum L1 qualifies as a Based Rollup. It's an architectural enhancement rather than a separate category.
Q: Does Based Rollup eliminate the need for sequencers entirely?
A: Not always. While final ordering happens on L1, some projects may still use proposers or aggregators to bundle transactions—but without exclusive control over inclusion order.
Q: How does Based Rollup affect user experience?
A: Users enjoy faster confirmations, lower fees, and stronger security guarantees without needing to understand backend complexities.
Q: Is Taiko the only project using Based Rollup?
A: Currently, Taiko is the most prominent example actively deploying this model. Others may follow as awareness grows and tooling matures.
Q: Will Based Rollups replace traditional Rollups?
A: Not necessarily. Different use cases demand different trade-offs. However, Based Rollups offer compelling advantages for applications prioritizing decentralization, security, and alignment with Ethereum’s core values.
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The Future of Based Rollups
Although Based Rollups are still in early development—with theoretical frameworks evolving and real-world deployments limited—their potential is undeniable. By leveraging Ethereum’s existing security and consensus strength, they offer a path toward truly decentralized, efficient, and secure scaling.
As DeFi applications demand faster settlements and stronger trust guarantees, Based Rollups are well-positioned to meet these needs. With continued research and ecosystem support, they could become a cornerstone of Ethereum’s modular future.
Core Keywords: Based Rollup, Ethereum liveness, L1-sequenced Rollup, ZK Rollup, Optimistic Rollup, Layer 2 scaling, Taiko, transaction finality