What is a layer 0 blockchain?

A layer 0 blockchain is a base network that other blockchains are built on top of or connected through. Where a layer 1 such as Bitcoin or Ethereum processes its own transactions, a layer 0 focuses on giving many chains a common foundation, such as shared security, standard building tools and a way to pass messages between them.

What is a layer 0 in crypto?

The term is used loosely. Finary describes layer 0 as the lowest layer of the blockchain stack, covering the networks and protocols that carry data between participants and support the security and interoperability of chains above it. In practice, crypto projects use the label for platforms whose main job is to host or link other chains rather than to run apps themselves.

It is not an official standard, and projects do not always agree on where they fit. Finary notes that Avalanche is sometimes called a layer 0 because it lets users launch custom chains, but Avalanche officially calls itself a layer 1.

What is the difference between layer 0 and layer 1?

A layer 1 blockchain handles consensus and transaction processing for its own users. Layer 2 networks sit on top to add speed or lower costs, as covered in what a layer 2 is. A layer 0 sits underneath and supports multiple layer 1 style chains at once.

Polkadot shows the idea clearly. Its relay chain is kept deliberately minimal, handling block production, scheduling, data availability and shared security. Separate chains called parachains run on it and share the relay chain's validator set, so they do not each need their own large group of validators. They exchange messages using a format called XCM. Interestingly, Polkadot's own wiki does not use the term layer 0. Read more in what Polkadot is.

What are some layer 0 examples?

Cosmos takes a different route. The Cosmos SDK is an open-source framework for building application-specific blockchains, usually paired with the CometBFT consensus engine. Chains built with it can talk to each other through the Inter-Blockchain Communication protocol (IBC) while keeping their own security and rules. Unlike Polkadot, each Cosmos chain normally secures itself.

Is LayerZero a layer 0 protocol?

Not in the same sense. LayerZero's docs describe it as an omnichain messaging protocol, a permissionless framework for moving information between blockchains. It works through endpoint contracts deployed on existing chains, plus verifier networks that apps choose themselves. It does not host other chains the way Polkadot does. See what LayerZero is for more.

As of November 2026, layer 0 remains a marketing and teaching shorthand rather than a strict category, so it helps to check what each project actually does.