Modular Blockchain Stack

A close look at the modular blockchain thesis. Celestia, EigenDA, Avail, restaking economics, rollup-as-a-service, the modular vs monolithic debate, and the rise of app-chains exemplified by dYdX's migration to Cosmos.

15 min · expert · part of Advanced Concepts

The Modular Thesis

For most of cryptocurrency's history, blockchain design assumed that one chain should do everything: execute transactions, achieve consensus, store data, and provide settlement. Bitcoin and Solana are paradigmatic monolithic chains. Each is a single integrated system that handles all four functions natively. The modular thesis argues for the opposite. It holds that specialized layers, each optimized for one function, will outperform integrated systems at scale. In the modular vision, execution happens on rollups, settlement happens on Ethereum L1, consensus is a function of whichever chain provides settlement, and data availability is delegated to a specialized DA layer like Celestia or EigenDA. Each layer can be independently upgraded, replaced, and scaled. The thesis is not just academic. By 2025, multiple modular projects had launched mainnets, captured significant TVL, and produced rollups that depend on them. The modular stack now sits alongside Solana and other monolithic systems as a credible architectural choice. Builders evaluating where to deploy must understand both options. This lesson walks through the major modular components in production today (Celestia, EigenDA, Avail), the economics of restaking that backstops EigenDA's security, the rollup-as-a-service ecosystem that lets new projects launch chains in days, and the debate between modular and monolithic approaches. It closes with the related "app-chain" thesis, exemplified by dYdX's well-known migration from an Ethereum L2 to a Cosmos sovereign chain in late 2023.

Also in this lesson

Celestia: The First DA Layer
EigenDA and Avail
The Restaking Economic Stack
Rollup-as-a-Service: Conduit, Caldera, AltLayer
Modular vs Monolithic and the App-Chain Thesis
For Deeper Reading

Key terms

Celestia: The first production data availability layer. Mainnet October 31, 2023. Uses data availability sampling and erasure coding to let light clients verify data availability with high cryptographic confidence. TIA token distributed via 580K-wallet airdrop.
Data Availability Sampling (DAS): A scheme where light clients verify a block's data is available by random sampling of erasure-coded shards. With high probability, unavailable data is detected without requiring full block download.
EigenDA: Data availability service built on EigenLayer restaking. Mainnet Q2 2024 (April 2024). First AVS launched. Operator stake requirement evolved from 320 ETH per node to 96 ETH as the network matured.
Avail: Data availability project that spun out of Polygon in 2023. Mainnet launched July 23, 2024 with AVAIL token TGE. Roadmap includes Avail Nexus (cross-rollup messaging) and Avail Fusion (Bitcoin-secured DA).
Liquid Restaking Token (LRT): Tokenized representation of restaked ETH (Ether.fi eETH, Renzo ezETH, Kelp rsETH, Puffer pufETH). Earns baseline ETH yield plus AVS yield. Total LRT TVL exceeded $14B at peak.
Kelp Hack (April 19, 2026): Exploit at Kelp DAO that drained approximately $6B of liquid restaking collateral, rippling through Ethereum DeFi and contributing to Aave's TVL decline from $30.5B to ~$20B.
Rollup-as-a-Service (RaaS): Commodity rollup deployment platforms: Conduit, Caldera, AltLayer. Handle sequencer infrastructure, DA integration, monitoring, and operations so customers can launch custom chains in days.
AltLayer Restaked Rollup: AltLayer's product where the rollup's sequencer set is itself an EigenLayer AVS. Adds restaked ETH backing as an additional security layer on top of underlying L1.
Monolithic Blockchain: Architecture where one chain handles execution, consensus, settlement, and data availability natively. Solana is the paradigmatic example. Argued to deliver simpler UX and cleaner composability than modular alternatives.
App-Chain: Sovereign chain dedicated to a single application or category. Cosmos SDK and Polkadot pioneered the model. Avalanche subnets extend it. Trades composability for control over the entire stack.
dYdX V4 Migration: dYdX's late-2023 migration from an Ethereum L2 (StarkEx-based V3) to a sovereign Cosmos chain (V4). The canonical example of the app-chain thesis at scale; V4 launched October 2023.
Vitalik's "Don't overload Ethereum's consensus" essay (May 2023): Vitalik Buterin's warning that AVSs should not require Ethereum L1 forking decisions, since this would create perverse pressure on social consensus. Shaped EigenLayer's formal position on legitimate slashing conditions.

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