Rollup
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In Brief
A rollup is a Layer 2 scaling solution that bundles ("rolls up") many transactions into a single batch processed off-chain, then posts compressed data back to the Layer 1 — lowering fees while inheriting the base chain's security.
What Is a Rollup?
A rollup is a Layer 2 scaling technology that bundles — or "rolls up" — hundreds or thousands of transactions into a single batch. The transactions are executed off the main chain, and only compressed summary data (plus a proof) is posted back to the Layer 1. This dramatically reduces fees and increases throughput while still relying on the base chain for security.
Rollups are widely regarded as the leading approach to scaling Ethereum, powering networks like Arbitrum, Optimism, Base, and zkSync.
How Does a Rollup Work?
Users submit transactions to the rollup (Layer 2).
The rollup executes them off-chain, away from the congested main chain.
Many transactions are compressed and batched together.
A summary of the batch — with proof of validity — is posted to the Layer 1.
The Layer 1 stores this data and provides final settlement and security.
Optimistic vs ZK-Rollups
| Feature | Optimistic Rollup | ZK-Rollup |
|---|---|---|
| Validity assumption | Assumes valid; can be challenged | Proven with cryptographic proof |
| Proof type | Fraud proofs | Zero-knowledge (validity) proofs |
| Withdrawal time | Longer (challenge period) | Faster (proof is final) |
| Complexity | Simpler to build | More computationally complex |
| Examples | Arbitrum, Optimism, Base | zkSync, Starknet, Polygon zkEVM |
Why Do Rollups Matter?
Lower fees — splitting costs across a batch makes each transaction far cheaper.
Higher throughput — many more transactions per second than the base chain.
Inherited security — settlement and data live on the secure Layer 1.
Better UX — fast, low-cost transactions for everyday use.
Rollups and Data Availability
A key part of a rollup's security is data availability — making sure the transaction data posted to the Layer 1 is accessible so anyone can verify or reconstruct the rollup's state. Innovations like Ethereum's "blobs" (EIP-4844) have lowered the cost of posting this data, making rollups even cheaper.
Rollups and Trust Wallet
Trust Wallet supports popular rollup-based Layer 2 networks, letting you transact with low fees and fast confirmations. As a non-custodial, multi-chain wallet covering 100+ blockchains, you can hold, send, swap, and bridge assets on rollups and their base chains alike — always keeping full control of your private keys.