Top Layer 2 Projects: A Rollup Model Comparison
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Here's the straight answer. The available dossier supports a comparison of the named networks based on their documented rollup models. It does not provide a current ranking by TVL, fees, or adoption. Arbitrum and Optimism are optimistic rollups. zkSync Era, Starknet, and Polygon zkEVM are ZK rollups. That gives you a practical starting point before you move funds.
What Is a Layer 2 and Why Does It Matter?
Ethereum is slow by design. The base chain prioritizes security and decentralization, and the throughput cost of that choice is real. That's where Layer 2 comes in.
Layer 2 protocols sit on top of Ethereum (the Layer 1), process transactions off-chain, and settle back to it when needed. The result: far higher throughput, significantly lower gas costs, and the same underlying security guarantees from Ethereum itself. The core mechanism is the rollup. Rollups execute hundreds or thousands of transactions off-chain, bundle them into a compressed batch, and post that batch to Layer 1. Ethereum acts as the security and data-availability layer. Batching is what makes fees cheap; settlement costs are spread across every transaction in the bundle.
Two rollup types dominate the landscape, and they make meaningfully different trade-offs.
Optimistic rollups (Arbitrum, Optimism, Base) assume transactions are valid unless someone submits a fraud proof. That assumption is efficient, but it introduces a roughly seven-day withdrawal delay to allow time for challenges.
- ZK rollups (zkSync Era, Starknet, Polygon zkEVM) generate cryptographic proofs that every transaction is valid before posting to Layer 1. No challenge window needed. Proof generation is computationally heavier, but finality is near-instant and mathematically guaranteed.
A quick note on sidechains: they're often confused with rollups, but they're different. A sidechain is a separate parallel blockchain with its own consensus mechanism and security model. It doesn't post transaction data to Ethereum. Rollups do. That's why rollups inherit Ethereum's security and sidechains don't.
Top Layer 2 Projects: A Rollup Model Comparison
The comparison below uses the dimension the dossier verifies: rollup model. It cannot rank these networks by TVL, fees, or adoption because it lacks up-to-date data on those metrics.
| Network | Rollup model |
|---|---|
| Arbitrum One | Optimistic |
| Optimism | Optimistic |
| zkSync Era | ZK |
| Polygon zkEVM | ZK |
| Starknet | ZK |
Optimistic rollups include Arbitrum and Optimism. They assume transactions are valid unless someone submits a fraud proof. That keeps execution efficient. A direct withdrawal from the rollup to Ethereum has a roughly seven-day challenge period. The wait leaves room for a challenge. Build that window into your plan when funds need to return to Ethereum.
ZK rollups include zkSync Era, Starknet, and Polygon zkEVM. They generate cryptographic proofs before posting transactions to Ethereum. No challenge window is required. Proof generation is heavier, while finality can be near-instant and mathematically guaranteed. This model matters when the withdrawal path is part of your decision.
Your route matters too. Moving within the same network is different from withdrawing through the rollup to Ethereum. That distinction is easy to miss, and it changes the wait you should plan for. Fees are another separate question. Rollups lower gas costs by batching transactions, but this dossier has no current fee comparison between named networks. Check the fee shown in your wallet before you approve a transfer.
These categories are not a quality ranking. The dossier does not verify current, comparable TVL, fee, or adoption metrics for all named networks. An ordered list of those criteria would be misleading. Use the model as a starting point, then check your chosen app, its supported network, and its fees before moving funds.
Storing L2 Assets: What to Know
If you hold assets on any of these networks, you need a wallet that actually supports them. Tangem Cold Wallet lists Arbitrum, Optimism, Base, zkSync Era, Starknet, and Polygon zkEVM among its supported networks, so you can store L2 tokens in cold storage rather than leaving them in a hot wallet.
Tangem supports 16,000+ cryptocurrencies and tokens across 91+ blockchain networks. The wallet connects to the Tangem mobile app via NFC, no USB, no Bluetooth, no battery required. For interacting with DeFi protocols on these Layer 2 networks, Tangem supports dApp connections via WalletConnect, with the WalletConnect network list including Arbitrum, Optimism, Base, and zkSync Era.
MetaMask supports Ethereum, Polygon, and other EVM-compatible networks with custom network configuration, and has over 30 million monthly active users, but it stores seed phrases and private keys locally in browser or device storage, which means phishing attacks and malicious extensions are real risks.
The right setup for most users: Tangem for long-term cold storage of L2 assets, and a hot wallet for active DeFi sessions where you're comfortable with the exposure.
FAQ
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Start with the application you want to use, then confirm its supported network and fees before moving funds. Say an Arbitrum dApp is your destination. Check that the app names Arbitrum, then review the fee in your wallet before you send assets. If you are unsure, make one small test transfer and confirm that it reaches the intended network. That extra step can keep a first transaction from landing on the wrong route.
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Before you send assets to a new network, make sure your wallet has enough of the network's fee asset for the transaction you plan to make. Picture one Base transaction. Look for the fee asset in your wallet before you begin, then review the displayed fee before you approve. If the required asset is missing, add it before you attempt the transfer. This is a quick check, but it matters before the first transfer.
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Plan around the roughly seven-day withdrawal window on an optimistic rollup such as Arbitrum or Optimism. That delay applies when moving funds back to Ethereum through the rollup's withdrawal process. A ZK rollup does not use that challenge window because it proves transaction validity before settlement.
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Tangem supports dApp connections through WalletConnect. Its listed WalletConnect networks include Arbitrum, Optimism, Base, and zkSync Era. Check that the dApp and the network in your wallet match before approving a connection.
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Confirm the wallet and dApp compatibility requirements before you begin. If a dApp only opens in a desktop browser, check that setup before you move assets to its network. That gives you time to choose another route before a transfer. Handle this while you are still planning the transaction.
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Check the network label in your wallet and at the receiving address before you confirm the transfer. This takes a moment. Say you are moving assets from Ethereum to Arbitrum. Match the network in your wallet to the receiving instructions, then check the destination again before approving. When you're moving assets between Ethereum and an L2, also confirm whether the destination expects a deposit, a withdrawal, or a transfer within the same network.
