How to bridge to Scroll? (ZK-rollup guide)

Understanding Scroll's ZK-Rollup Architecture

1. Scroll is a permissionless, EVM-equivalent ZK-rollup that generates cryptographic proofs off-chain to verify transaction batches before submitting them to Ethereum mainnet.

2. Its architecture separates execution from verification: transactions execute on Scroll’s L2 node while validity proofs are computed by dedicated provers using zk-SNARKs.

3. Every block on Scroll includes a SNARK proof published to Ethereum, ensuring data availability and state integrity without trusting operators.

4. Unlike optimistic rollups, Scroll does not rely on fraud challenges or time-based dispute windows—finality is achieved as soon as the proof is verified on Ethereum.

5. The system uses a custom prover written in Rust and leverages Plonky2 for recursive proof composition, enabling efficient aggregation of large batches.

Supported Bridging Methods

1. The official Scroll Bridge is the primary method, integrated directly into Scroll’s interface and supporting ETH, USDC, DAI, WETH, and other whitelisted ERC-20 tokens.

2. Users initiate bridging from Ethereum mainnet by connecting a wallet such as MetaMask, selecting the token and amount, and confirming two transactions: an approval and a deposit.

3. Deposits typically take 15–30 minutes to appear on Scroll due to batch processing intervals and proof generation latency.

4. Third-party bridges like Orbiter Finance and Bungee support Scroll but require manual verification of contract addresses and may carry additional slippage or fee structures.

5. Native token bridging via LayerZero is not supported; Scroll explicitly discourages use of omnichain messaging protocols for asset transfers due to trust assumptions incompatible with ZK-security models.

Wallet and Network Configuration

1. MetaMask remains the most widely tested wallet; users must manually add Scroll Sepolia testnet or Scroll mainnet RPC details, including chain ID 534352 for mainnet.

2. RPC endpoints are publicly documented on Scroll’s GitHub and require no API keys—nodes are run by community validators and Scroll Labs’ infrastructure.

3. Wallets must recognize EIP-1559 transaction formats; legacy gas pricing is unsupported, leading to failures if users override gas settings incorrectly.

4. Hardware wallets like Ledger work only when used through MetaMask’s browser extension with WebUSB enabled—direct dApp connection is not supported.

5. Address derivation follows standard Ethereum paths (m/44'/60'/0'/0), ensuring compatibility with existing key material and recovery phrases.

Security Considerations During Bridging

1. Users must verify they are interacting with scroll.io and not phishing domains mimicking the official bridge UI—typosquatting attempts have targeted Scroll since mainnet launch.

2. Contract addresses for the Scroll Bridge are immutable and published across multiple trusted sources: Etherscan, Scroll’s GitHub, and the Scroll Explorer.

3. No private key or seed phrase should ever be entered on any bridging interface—legitimate tools never request this information.

4. Reorg protection is built into Scroll’s verifier contract: proofs referencing Ethereum blocks subject to reorganization are rejected automatically.

5. Failed deposits due to insufficient ETH for gas on Ethereum will remain pending until manually canceled or retried; Scroll’s explorer provides status tracking for each deposit hash.

Frequently Asked Questions

Q: Can I bridge NFTs to Scroll?Scroll does not support NFT bridging at the protocol level. Only fungible ERC-20 tokens listed in the official bridge whitelist are permitted.

Q: Why does my deposit show “pending” for over an hour?This usually occurs when Ethereum mainnet experiences congestion, delaying the confirmation of the deposit transaction. Scroll only processes deposits after the initiating tx has at least one confirmation.

Q: Is it safe to use the Scroll Bridge with a hardware wallet connected via WalletConnect?WalletConnect v2 is supported, but signing must occur on-device. Some mobile wallets fail to render Scroll’s signature requests correctly—desktop MetaMask with Ledger is strongly recommended.

Q: Do I need to claim tokens after bridging?No. Tokens appear automatically in your Scroll wallet once the deposit is finalized and the proof is verified. There is no separate claim step.