Layer2 Intro: Why ETH Needs Scaling — Comparing 5 Major Solutions

You do a Uniswap trade on ETH and spend $30 in Gas fees. You think: that’s more expensive than bank fees — what’s the blockchain advantage? The issue isn’t ETH itself — ETH’s main chain (Layer1) is indeed too slow and expensive, but Layer2 scaling solutions are addressing this problem.

This article helps you understand why ETH needs scaling and the characteristics and prospects of 5 major Layer2 solutions.

1. Why ETH Needs Scaling

1.1 ETH’s Performance Bottleneck

ETH main chain core data:

• TPS: ~15-30 (theoretically higher but practically ~15)
• Average Gas fees: Normal periods $2-5, peak periods $50-200+
• Confirmation time: ~12 seconds per block

Compare: VISA credit card network handles ~65,000 TPS, major payment processors peak at ~540,000 TPS. ETH’s 15 TPS is根本 insufficient for large-scale use.

1.2 Why Can’t We Just Increase ETH Main Chain TPS

Increasing TPS has two methods, but both have costs:

• Increase block size: Each block contains more transactions → but nodes need to store more data → decentralization decreases (only large institutions can run nodes)
• Shorten block time: Faster block production → but nodes can’t verify fast enough → security decreases

The ETH community chose another approach: maintain main chain security and decentralization, move transaction execution to Layer2. Layer1 handles only consensus and data storage; Layer2 processes大量 transactions.

This is ETH’s scaling roadmap: Layer1 as the secure foundation, Layer2 as the performance accelerator.

1.3 Layer2 Core Principle

Layer2’s core logic is simple:

1. Users transact on Layer2 (fast speed, low fees)
2. Layer2 batches大量 transactions (rollup), submitting a summary to Layer1
3. Layer1 verifies the summary’s correctness (ensuring security)
4. If Layer2 has problems, users can recover assets from Layer1 (security guarantee)

Key understanding: Layer2 inherits its security from the ETH main chain. Even if Layer2 operators act maliciously or go offline, your assets can still be recovered from the ETH main chain. This is the fundamental difference between Layer2 and sidechains — sidechains have their own independent consensus mechanism with independent security; Layer2 depends on ETH main chain security.

2. Comparison of 5 Major Layer2 Solutions

2.1 Arbitrum (ARB) — Most Mature Layer2 Ecosystem

Technology: Optimistic Rollup

Core Features:

• Optimistically assumes all transactions are correct, default acceptance
• If someone finds a problem, they can submit a challenge within 7 days (fraud proof)
• After the 7-day challenge period, transactions are最终 confirmed
• Withdrawal to ETH main chain requires 7-day waiting (challenge period)

Advantages:

• Richest ecosystem: Most DeFi, NFT, and gaming applications
• Highest TVL: Long-term #1 TVL among all Layer2s
• Developer-friendly: Fully EVM-compatible, ETH DApps migrate nearly seamlessly
• Large user base: Leading active user count

Shortcomings:

• 7-day withdrawal waiting: Withdraw from Arbitrum to ETH requires 7 days (third-party bridges can fast-withdraw but cost extra)
• No data compression: Transaction data occupies more Layer1 space than zkRollup
• Sequencer dependency: Arbitrum has a centralized sequencer ordering transactions — downtime affects user experience

2.2 Optimism (OP) — Public Interest-Driven Layer2

Technology: Optimistic Rollup

Core Features:

• Similar to Arbitrum, using optimistic verification scheme
• 7-day challenge period
• Launched OP Stack — an open-source Layer2 framework

Advantages:

• OP Stack ecosystem: Base (Coinbase’s Layer2), Zora, Mode, and other chains built on OP Stack, forming a superchain ecosystem
• Public interest fund: Part of revenue funds public goods
• Transparent governance: Relatively open DAO governance

Shortcomings:

• Ecosystem scale smaller than Arbitrum: Slightly lower TVL and active users
• Same 7-day withdrawal waiting
• Same Sequencer centralization issue

2.3 zkSync (ZK) — Most Technologically Advanced Layer2

Technology: zkRollup (Zero-Knowledge Proof Rollup)

Core Features:

• Uses zero-knowledge proofs to verify transaction correctness
• Each batch of transactions includes a mathematical proof; Layer1 verifies the proof to confirm correctness
• No 7-day challenge period needed — the proof itself is evidence
• Higher data compression efficiency, lower Gas fees

Advantages:

• Fast withdrawal speed: No 7-day wait, completed in hours
• Lower Gas fees: ZK proof compression is more efficient
• Theoretically superior technology: ZK proofs are a major cryptographic breakthrough
• Large future potential: ZK technology can support更多 advanced features

Shortcomings:

• Ecosystem still developing: TVL and active application count lag behind Arbitrum
• EVM compatibility not perfect: zkEVM is improving but still has limitations
• High proof generation cost: Generating ZK proofs requires大量 computation
• Technical complexity: High ZK technology barrier

2.4 Base — Coinbase’s Layer2

Technology: Optimistic Rollup built on OP Stack

Core Features:

• Layer2 launched by Coinbase exchange
• Uses OP Stack framework
• Launched August 2023, extremely fast growth

Advantages:

• Coinbase endorsement: Supported by the largest compliant US exchange
• No token: Base doesn’t issue its own token
• Good user experience: Coinbase users can directly access Base
• Fast growth: TVL quickly entered top 5

Shortcomings:

• Fully dependent on Coinbase: High centralization
• No token incentives: Lacks token incentive mechanisms
• Feature limitations: Positioned as simple and easy to use

2.5 Blast — Yield-Built-In Layer2

Technology: OP Stack-based Optimistic Rollup

Core Features:

• Automatically generates yield on ETH and USDC deposits (ETH ~4% annual, USDC ~5% annual)
• Yield来自 Lido and MakerDAO
• Launched late 2023, controversial

Advantages:

• Auto-yield on deposits: Funds on Blast automatically earn returns
• Attracts fund inflows: Yield mechanism attracts大量 funds quickly
• Airdrop expectations: Team promised airdrops

Shortcomings:

• Security controversy: Underlying risks of the yield mechanism questioned
• High centralization: Control concentrated in team during initial phase
• Polarized community评价

3. Layer2 Core Metrics Comparison

Metric	Arbitrum	Optimism	zkSync	Base	Blast
Technology	Optimistic	Optimistic	ZK	Optimistic	Optimistic
Withdrawal wait	7 days	7 days	Hours	7 days	7 days
Gas fees	Low	Low	Very low	Low	Low
TVL	Highest	High	Medium	Fast growth	Fast growth
EVM compat	Perfect	Perfect	Limited	Perfect	Perfect
Ecosystem maturity	Most mature	Fairly mature	Developing	Fast developing	Initial
Decentralization	Medium	Medium	Low	Low	Low

4. How Beginners Can Use Layer2

4.1 Basic Operation Flow

Steps to use Layer2:

1. Have ETH assets on the main chain
2. Transfer ETH from main chain to Layer2 via the official bridge
3. Use various applications on Layer2 (low fees, fast speed)
4. Transfer assets back to ETH main chain when needed

4.2 Which Layer2 to Choose

Beginner recommendations:

• Daily use: Arbitrum (richest ecosystem, most applications)
• Lowest Gas fees: zkSync (lowest fees)
• Coinbase users: Base (most convenient entry)
• Exploring new ecosystems: Try Blast or other emerging Layer2s

4.3 Safety Notes

• Only use official bridges for cross-chain transfers (don’t use unverified bridges)
• Test with small amounts first (cross $50-100 to try the process)
• Note withdrawal waiting times (Optimistic Rollup requires 7 days)
• Don’t put all assets on Layer2 (large amounts safer on ETH main chain)

Practical Case: Moving from ETH Main Chain to Arbitrum

1. Open bridge.arbitrum.io (official bridge)
2. Connect MetaMask wallet
3. Enter ETH amount to transfer
4. Confirm transaction (need to pay ETH main chain Gas fee, ~$2-5)
5. About 10 minutes later, ETH arrives on Arbitrum
6. Use GMX, Uniswap, and other apps on Arbitrum
7. When withdrawing to ETH main chain, use the official bridge and wait 7 days

The whole process is like transferring money from a bank (ETH main chain) to a digital payment app (Arbitrum) — convenient for daily spending on the payment app, but large deposits are safer at the bank.

Summary and Action Advice

Layer2 isn’t ETH’s replacement — it’s ETH’s accelerator. It inherits ETH’s security while providing better performance and lower fees.

For beginners:

1. Familiarize with basic operations on ETH main chain first
2. Then try Arbitrum or Base as your first Layer2 experience
3. Cross-chain with small amounts to test — don’t transfer all assets to Layer2 at once
4. Understand Optimistic vs ZK differences: 7-day waiting vs hours withdrawal — this is the most important user experience difference
5. Layer2 is ETH ecosystem’s future direction, but it’s still in rapid development

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