What Are Modular Blockchains? A Beginner's Guide to the 2025 Architecture Trend

For a long time, the dream was to build a single blockchain that could do everything. A supercomputer that would be the foundation for the entire decentralized internet. But what if that was the wrong approach? What if the future is not one giant monolithic blockchain, but a network of smaller, specialized, and interconnected chains?

A monolithic blockchain is a network where all core functions, transaction execution, consensus, and data availability are handled within a single vertically integrated system. These networks process every part of the blockchain lifecycle in one place, with Bitcoin and early Ethereum serving as the most notable examples. This stands in contrast to the new modular approach, where these functions are broken up and handled by different specialized layers.

This article will provide a beginner’s guide to the concept of modular blockchains, explaining the different layers of the modular stack, the benefits of this new architecture, and the key projects leading the modular revolution.

The Three Layers of a Blockchain

A Simple Framework

To understand the modular thesis, you first need to understand that a blockchain does three main things. Execution is the layer where transactions are actually computed, such as when a smart contract is run. Settlement is the layer where transactions are finalized and disputes are resolved. Data availability is the layer that ensures all of the data for a transaction is available for anyone to see and verify.

In early blockchain designs like Ethereum 1.0 and Bitcoin, all nodes were required to store and verify the entire state, perform execution, and validate consensus. This monolithic model ensures strong security but inherently limits scalability. Ethereum processes roughly 15 transactions per second, partially constrained by its requirement to publish all transaction data on-chain for availability.

The challenges of blockchain performance and cost are systemic consequences of architectural decisions. During peak activity on Ethereum, users often face extreme fees and delayed confirmations, caused not by bad code but by the architectural decision to bundle execution, consensus, and data availability into a single system.

The Modular Thesis: Do One Thing, and Do It Well

The Core Idea

The modular thesis suggests that instead of having one blockchain that does all three functions, it is better to have a stack of specialized layers where each layer is optimized to do one thing and do it well. By decoupling these components, modular blockchains allow each layer to focus on doing one job well.

According to Celestia co-founder Mustafa Al-Bassam, for the past decade, crypto has been bottlenecked by an endless loop of new monolithic L1 smart contract platforms, each racing to the bottom to sacrifice decentralization and security to provide cheaper transaction fees. The modular approach breaks this pattern by allowing specialization without compromise.

Monolithic vs Modular stack:source: Celestia

The Ethereum-Centric Model

The most popular version of the modular thesis is emerging in the Ethereum ecosystem, creating a clear division of labor. The execution layer is where Layer-2 networks, such as Arbitrum, Optimism, and Base, are highly optimized for fast and cheap transaction execution. By offloading execution to a secondary layer while leveraging Celestia for data availability and consensus, rollups achieve high throughput without sacrificing security, allowing traders to buy ETH or onramp crypto more affordably due to reduced gas costs.

The settlement layer is the role of the Ethereum mainnet, acting as a universal and highly secure settlement layer for all the L2s built on top of it. Settlement and final security are typically provided by Ethereum itself or another robust Layer 1. This arrangement allows Ethereum to focus on what it does best: providing maximum protection and finality.

The data availability layer represents a new and exciting area of innovation. Celestia launched its Mainnet Beta called Lemon Mint in October 2023, marking the rollout of the first modular data availability network. Projects like Celestia are building specialized blockchains designed to do nothing but store transaction data and make it available, which can make L2 transactions even cheaper.

Understanding Data Availability: The Critical Component

Data availability refers to ensuring all network participants have the necessary data to verify a block. For modular blockchains, Layer-2 rollups, or light clients, data availability ensures that summarized transaction data added to the blockchain represents valid transactions without requiring all nodes to download all the data.

The innovation that makes modular data availability practical is data availability sampling. Data Availability Sampling allows you to easily verify large blocks with minimal data, and hence boost scalability. This technique enables light clients to verify that data is available without downloading entire blocks, a breakthrough that makes scalable data availability economically feasible.

Blocks in Celestia can grow to several megabytes without compromising security or decentralization. A recent report has it that there has been an 8MB upgrade, a major leap from Ethereum’s approximate 15 MB block gas limit. This dramatic increase in data capacity comes without proportionally increasing the verification burden on nodes, solving a problem that plagued monolithic designs.

The Rise of Celestia: Leading the Modular Revolution

Celestia introduces a new approach to blockchain by decoupling consensus and data availability from execution. The project has emerged as the flagship example of modular blockchain infrastructure. Celestia’s Mainnet launched in October 2023, and by April 2025, it introduced mamo-1, a public testnet that achieved 21.33MB transactions per second throughput with 128MB blocks, significantly outperforming the mainnet.

Celestia uses TIA tokens as a crucial component. To make data available on Celestia, rollup developers submit PayForBlobs transactions containing sender identity, data to be made available, data size, namespace, and signature, paying a fee using TIA tokens. This creates an economic model where developers can bootstrap chains using TIA as a gas token, similar to using ETH on Ethereum-based rollups.

Celestia price chart. Source: CoinMarketCap

The Benefits of a Modular World

Scalability: Breaking Through the Bottleneck

By breaking up the work, a modular blockchain can process a much higher volume of transactions than a monolithic one. The result is horizontal scalability: multiple rollups can post data to Celestia simultaneously, without competing for execution or compute resources. This is fundamentally different from monolithic chains, where all applications compete for the same block space.

Rollups such as Optimism and Arbitrum address execution limitations but still rely on Ethereum for data availability, posting calldata to Layer 1, which remains expensive at $0.25 to $0.50 per kilobyte. By using specialized data availability layers, including Celestia, these costs can be reduced by orders of magnitude, making previously uneconomical applications viable.

Specialization and Sovereignty: Customization Without Compromise

The modular approach allows for the creation of highly specialized blockchains optimized for specific use cases. High-performance gaming applications require fast execution and low latency. Modular designs enable gaming blockchains to focus on user experience while relying on shared data availability and consensus layers.

Celestia enables sovereign chains, which are independent blockchains that use Celestia’s infrastructure but make their own decisions about execution. This sovereignty means that application-specific chains can have their own rules and governance, giving them a degree of independence while still benefiting from shared security and data availability infrastructure.

Organizations seeking private or permissioned blockchains can leverage modular frameworks to build tailored solutions that integrate seamlessly with public networks. This hybrid approach balances privacy with interoperability. Developers no longer face the binary choice between public permissionless chains and completely isolated private chains.

Developer Empowerment and Rapid Deployment

A core tenet of Celestia’s vision is to simplify blockchain deployment, enabling anyone to launch and deploy their own blockchain easily. Developers can use TIA tokens instead of issuing additional tokens to support the launch of their blockchain. This dramatically lowers the barrier to entry for launching new chains.

You can easily deploy a blockchain as straightforwardly as a smart contract by using the high-throughput data availability of Celestia. What previously required assembling a validator set, building consensus infrastructure, and solving data availability challenges can now be accomplished by leveraging modular infrastructure that’s already running at scale.

Leading Modular Blockchain Projects

Beyond Celestia, the modular ecosystem includes several key players. The best modular blockchains are Arbitrum, Manta Network, Celestia, Optimism, and Berachain, designed to separate core blockchain functions like execution, consensus, and data availability to improve speed, reduce costs, and increase flexibility.

Manta Pacific is a Layer 2 solution on Ethereum optimized for EVM-native ZK applications, depending on Celestia for data availability and eventually moving to a zkEVM on top of Celestia via the Polygon Chain Development Kit. This demonstrates how modular components can be combined in novel ways to create specialized solutions.

Berachain launched in February 2025 with a triple-token economy of BERA for gas, BGT for governance, and HONEY as a stablecoin, supporting DeFi, NFT, and Layer 2 solutions. These projects represent different approaches to implementing modular principles while optimizing for different use cases.

Conclusion

The modular thesis is about unbundling the functions of a blockchain into a stack of specialized layers. Modular blockchains are not just a technical innovation; they represent a shift in how we think about decentralization. Rather than forcing one chain to do everything, modular systems embrace diversity, specialization, and scalability for a faster and more efficient fiat-to-crypto onramp.

The modular approach is the key to building a more scalable, flexible, and decentralized internet of value. The future is not a single dominant blockchain but a vibrant and interconnected internet of blockchains, with Ethereum positioned as the global settlement layer. This shift reflects how modular design is becoming central to real-world blockchain deployments.

As tooling, standards, and adoption improve, modular architecture may become the default for the next generation of blockchain applications. The trend has accelerated dramatically between 2023 and 2025, with multiple production-ready modular infrastructure layers now available for developers to build upon.

FAQ

What is a modular blockchain?
A modular blockchain separates core blockchain functions, transaction execution, consensus/settlement, and data availability into distinct, specialized layers optimized independently.​

What is the difference between a modular and a monolithic blockchain?
Monolithic blockchains perform all key functions in a single layer, processing transactions, consensus, and data storage together.

What is a Layer-2?
A Layer-2 (L2) network is a secondary framework built on top of a Layer-1 blockchain (like Ethereum) to handle transaction execution off-chain or semi-off-chain, helping increase throughput and reduce fees.​

What is a data availability layer?
A data availability layer is a specialized blockchain layer responsible for ensuring that transaction data is available for download and verification by all participants.

What is Celestia?
Celestia is the first modular blockchain designed specifically as a data availability and consensus layer, decoupled from execution. Launched in October 2023, it enables rollups and sovereign blockchains to use its scalable and secure data availability infrastructure, improving scalability and lowering costs while preserving decentralization and security.