اختيار Layer 2

There are many Layer 2s, each with different trade-offs. Choosing one means weighing security, cost, speed, and ecosystem.

This lesson gives you a framework to compare them sensibly.

The first question is security. Rollups inherit L1 security; sidechains and validiums do not fully.

• ZK rollup: strongest, validity proofs
• Optimistic rollup: strong, fraud proofs
• Sidechain: own validators, weaker

Fees vary widely. L2s that use blobs (post-EIP-4844) and efficient compression are cheaper.

Compare typical swap and transfer costs on each network, not just headline claims.

How fast can you safely move funds back to L1?

• ZK rollups: fast finality, quick withdrawals
• Optimistic rollups: ~7-day withdrawal (or pay a fast-bridge fee)

If you need to exit quickly, this matters a lot.

EVM equivalence means existing Ethereum contracts and tools work unchanged.

Optimistic rollups (Arbitrum, Optimism) and many ZK rollups now offer strong EVM compatibility, easing migration.

A chain is only as useful as its ecosystem. Check which DEXs, lending markets, and stablecoins are deployed and how much liquidity exists.

Deep liquidity means low slippage and a healthy DeFi environment.

Most L2s today use a single sequencer to order transactions, which is a centralization risk.

Ask whether the sequencer can censor transactions and whether there is a path to decentralize it and an L1 escape hatch.

For builders, consider the availability of RPC providers, block explorers, indexers, oracles, and SDKs.

A mature toolchain accelerates development and reduces friction when shipping a dApp.

How easily can users get funds onto the chain? Look at the canonical bridge, supported third-party bridges, and direct fiat on-ramps.

Smooth onboarding strongly affects user adoption.

Different needs favor different chains:

• High-value DeFi: prioritize security and liquidity
• Gaming/social: prioritize cheap, fast transactions
• Quick exits: favor ZK rollups

Choosing an L2 means balancing security model, cost, finality, EVM compatibility, ecosystem, sequencer decentralization, and tooling against your specific use case.

There is no single best L2 — only the best fit. Next course: Cross-Chain and Bridges.

Test your L2 selection reasoning.

You learned to weigh:

• Security model (rollup vs sidechain)
• Cost, finality, and withdrawal time
• EVM compatibility and tooling
• Ecosystem, liquidity, and sequencer decentralization
• Match the L2 to your use case

Course complete! Next: Cross-Chain and Bridges.