Definition
Alternative data availability is a mechanism in which blockchain transaction data is published and stored on a dedicated data layer that is distinct from the chain handling execution and state transitions. Instead of embedding all transaction data directly on a monolithic blockchain, the system relies on an external or modular data availability provider that guarantees data publication and retrievability. This separation allows the execution environment to assume that data is accessible without itself bearing the full cost and complexity of storing it.
In this model, the alternative data availability layer focuses on ensuring that transaction data is widely distributed, verifiable, and resistant to censorship or withholding. The execution chain or rollup then references this external data layer when processing transactions and updating state. This mechanism is particularly relevant in modular blockchain architectures, where components such as consensus, execution, and data availability are decoupled and can be provided by specialized networks like Celestia.
Context and Usage
Alternative data availability is used to scale blockchain systems by offloading the heavy burden of data storage and propagation from the main execution environment. By delegating data publication to a specialized layer, rollups and other off-chain execution environments can maintain security assumptions tied to data availability while reducing on-chain resource consumption. This enables higher throughput and more flexible designs than traditional monolithic chains that handle execution and data availability together.
In practice, a rollup or similar system commits cryptographic references to data stored on the alternative data availability layer, while nodes and light clients verify that the data is actually available. Networks such as Celestia are designed specifically to provide this type of service, offering a shared data availability layer that multiple execution environments can rely on. The mechanism is central to emerging modular blockchain ecosystems, where interoperability and shared security are built around common data availability infrastructure.