Layer 3

A Layer 3 (L3) is a blockchain deployed on top of a Layer 2 network, adding a third tier to the blockchain scaling stack. While a Layer 2 exists to scale an entire base chain, a Layer 3 usually serves a single application or ecosystem with its own dedicated environment.

The stack works from the bottom up. A Layer 1 such as Ethereum provides consensus and final settlement, Layer 2 rollups batch transactions and post proofs or compressed data back to it, and a Layer 3 settles to the Layer 2 beneath it. Security flows down this chain: an L3 is only as trustworthy as the L2 it settles to, and its data availability choices matter. Many L3s keep transaction data off the base chain to cut costs, which weakens guarantees compared to a full rollup.

Teams choose an L3 for app-specific control. Common motivations include a custom gas token, dedicated throughput that is not shared with unrelated apps, built-in privacy features, or logic tuned for gaming, with fees that are often lower still than on the underlying L2.

Live examples include Arbitrum Orbit chains that settle to Arbitrum One, ZK Chains (previously called Hyperchains) built with ZKsync technology, and appchains launched on Base.

Layer 3s remain debated. Ethereum co-founder Vitalik Buterin has cautioned that stacking layers does not automatically multiply scalability, and each extra tier adds bridging steps and fragments liquidity across chains. A solid grasp of the Layer 2 a project settles to, and the rollup design behind it, is the natural starting point for evaluating any Layer 3.