TECHNOLOGIES

Layer 2

Layer 2 (L2)

A chain built on top of a base blockchain that processes transactions cheaply and fast, then posts proofs back to the base layer for security.

Last reviewed: 2026-06-02 byKevin Riedl wiki β†—

A Layer 2 is a blockchain that borrows security from a Layer 1 (usually Ethereum) instead of running its own consensus from scratch. The L2 executes transactions off the base chain, bundles them, and posts the result back to L1. Users get the security guarantees of Ethereum at a fraction of the cost and with much higher throughput. L2s exist because base-layer block space is scarce and expensive: when Ethereum is busy, a simple transfer can cost more than the thing being transferred.

The dominant design is the rollup, which comes in two flavours. Optimistic rollups (Arbitrum, Optimism, Base) assume transactions are valid and allow a challenge window during which anyone can dispute a fraudulent batch. ZK rollups use a zero-knowledge proof to mathematically prove each batch is valid before it lands on L1, which removes the challenge delay at the cost of heavier proving infrastructure. Optimistic is simpler and cheaper to build on today; ZK is where the technology is heading.

Wavect has shipped to production on an L2 (Boba Network), including its hybrid compute model that lets a smart contract call off-chain code mid-execution. That pattern is powerful for bringing real-world data or heavy computation into a contract, and it is genuinely hard to operate safely. If a vendor pitches an L2 deployment as a free scaling win, ask how withdrawals to L1 work, what the finality delay is, and who runs the sequencer. Our blockchain work covers L2 selection and deployment.

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FAQs

FAQs

A chain that runs transactions cheaply off a base blockchain and posts proofs back to it for security. You get most of Ethereum’s trust guarantees at a fraction of the fees and far higher throughput.
Optimistic rollups assume validity and allow a challenge window, which makes withdrawals to L1 slow (often a week) but keeps the system simple and cheap to build on. ZK rollups prove validity cryptographically, removing the delay at the cost of heavier proving infrastructure. ZK is the direction of travel; optimistic is the pragmatic default today.
No. You inherit a new sequencer to trust, a withdrawal delay back to L1, and chain-specific quirks to re-test against. The fee savings are real and large, but treat an L2 as a deployment target with its own operational model, not a magic switch.