Skip to main content

​
What Are Based Appchains?

We define a “based rollup” as one that primarily uses based sequencing, where (1) Ethereum L1 proposers have preferential access to sequencing rights and (2) the rollup reorgs and finalizes in lockstep with Ethereum L1. A based appchain applies that pattern to application-specific execution environments:
  • Settlement-aligned sequencing – Ordering rights ultimately flow from the settlement layer, preserving Ethereum’s neutrality and permissionless access
  • Shared finality – Appchains adopt the settlement chain’s canonical view, reorging and finalizing whenever the base layer does
  • Ethereum-native guarantees – By leaning on Ethereum’s validator set and PBS ecosystem, appchains inherit familiar liveness, censorship resistance, and security assurances
Implementations can evolve over time, but the goal is constant: settlement-driven sequencing with atomic finality.

​
Why Build a Based Appchain?

Based appchains combine the sovereignty of dedicated blockspace with the composability of deploying directly on the settlement layer:
  • Scalability – Tune gas limits and block cadence to handle your application’s peak throughput without noisy neighbors
  • Stability – Dedicated execution avoids cross-app congestion and fee spikes
  • Accessibility – Users keep assets on the settlement layer and interact with familiar tooling while your appchain delivers tailored UX
  • Profitability – Capture MEV and fee flows generated by your application instead of donating them to shared infrastructure
  • Sovereignty – Control upgrades, token economics, and governance policies while inheriting settlement security
  • Simplicity – Deploy once; supporting infrastructure handles cross-chain orchestration, state sync, and RPC exposure

​
Why Based Matters

Key advantages highlighted across the based rollup research community include:
  • Atomic synchronous composability – Applications across chains can interact in a single transaction instead of waiting for bridge confirmations
  • Improved developer experience – Based sequencing enables synchronous composability with standard EVM tooling, so developers can target familiar interfaces without bespoke bridge workflows
  • Custom execution – Tune block times, gas limits, and execution environments without fragmenting liquidity
  • Credible neutrality & security – Sequencing leverages Ethereum’s validator set, aligning incentives instead of outsourcing trust to new sequencer networks

​
Sovereignty vs. Settlement

​
Sovereignty Benefits

  • Dedicated execution environment – No competition for block space with unrelated apps
  • Custom gas models – Set fee markets, native tokens, and subsidy policies
  • Independent infrastructure – Optimize clients, tooling, and observability for your needs
  • Governance control – Choose upgrade cadence and permissioning

​
Settlement Layer Benefits

  • Security inheritance – Finality and reorg resistance mirror the settlement layer
  • Liquidity access – Users keep assets on the settlement chain while interacting with your appchain
  • Composability – Contracts can call into settlement-layer protocols atomically
  • User familiarity – Wallets and tooling already support the settlement ecosystem

​
Based Appchain Model

​
Traditional L2s (Shared Infrastructure)

Problems:
  • Resource competition (the “noisy neighbor” problem)
  • Limited customization options (block times, fee markets, token economics)
  • Shared failure domains (sequencer downtime impacts every app)

​
Based Appchains (Dedicated Infrastructure)

Benefits:
  • Dedicated resources for each application
  • Full control over execution parameters
  • Isolated failure domains (one chain’s outage doesn’t stop the others)
  • Direct settlement layer interaction for liquidity and finality

​
Choosing Your Settlement Layer

Picking a settlement layer is ultimately a business and product decision. Factors teams usually weigh include:
  • Security vs. cost – Higher-security networks often come with higher gas fees; lighter-weight options trade some assurances for lower cost
  • Ecosystem compatibility – Tooling, wallets, and liquidity pools already live on a specific network; aligning with your users minimizes friction
  • Operational guarantees – Finality speed, upgrade cadence, and infrastructure maturity impact how your appchain behaves day to day
For the networks Pylon currently supports, see the table in the Chain Setup guide.

​
Security, Liveness, and Neutrality

Because sequencing ultimately flows through the settlement layer, based appchains inherit:
  • Settlement neutrality – Ordering rights follow the same rules as the base chain, rather than being concentrated in a bespoke sequencer
  • Censorship resistance – Any safeguards the settlement layer offers (inclusion lists, fallback proposers, watchdogs) automatically apply to appchain transactions
  • Liveness guarantees – If the settlement layer advances, so does the appchain; there’s no separate sequencer that can stall progress
  • Aligned incentives – Fees and MEV are reconciled through the settlement layer’s economics, keeping incentives consistent with the broader ecosystem

​
Ecosystem Momentum

Major ecosystem players are aligning around based sequencing and synchronous execution. Initiatives like Fabric, research from Ethereum Foundation contributors, and widespread builder interest (Base, Taiko, Scroll, and more) signal that based appchains are a strong path forward to reconnecting fragmented liquidity while keeping Ethereum at the center. Launching on Pylon today means benefiting from this rapidly compounding tooling and standards work.

​
The Appchain Advantage

Based appchains unlock a unified experience:
  • Sovereign – Own your execution, governance, and economics
  • Scalable – Allocate blockspace exclusively to your use case
  • Composable – Treat settlement-layer contracts as local state thanks to synchronous reads (and soon writes)
Applications can deliver tailored UX without sacrificing the liquidity, credibility, or developer mindshare of the Ethereum ecosystem.

​
Next Steps