Rollup Types Compared
Rollups batch hundreds of transactions off-chain and post a compressed summary to L1. The key difference: Optimistic rollups assume all transactions are valid and allow a challenge window, while ZK rollups generate a cryptographic proof of correctness. Each approach has fundamentally different tradeoffs.
⚙️ Batch Simulator
L1 Cost (single tx)
$4.20
Optimistic (per tx)
$0.08
ZK (per tx)
$0.12
Savings
98%
Batch L1 Cost
$42
⏱️ Finality Timeline
Optimistic Rollup
• Instant soft-confirmation (~2s)
• 7-day challenge period for withdrawals
• Fraud proofs only generated on dispute
• Simpler to build, EVM-equivalent
• Used by: Arbitrum, Optimism, Base
• 7-day challenge period for withdrawals
• Fraud proofs only generated on dispute
• Simpler to build, EVM-equivalent
• Used by: Arbitrum, Optimism, Base
ZK Rollup
• Instant soft-confirmation (~2s)
• Proof finality in minutes-hours
• Validity proof generated for every batch
• Complex to build, requires circuits
• Used by: zkSync, StarkNet, Scroll, Linea
• Proof finality in minutes-hours
• Validity proof generated for every batch
• Complex to build, requires circuits
• Used by: zkSync, StarkNet, Scroll, Linea
🔑 Key Tradeoff: Trust vs Compute
SECURITY MODEL
Optimistic: Trust but verify. Anyone can challenge.
ZK: Don't trust, verify everything mathematically.
ZK: Don't trust, verify everything mathematically.
WITHDRAWAL TIME
Optimistic: 7 days (or use fast bridge).
ZK: Minutes to hours (once proof posts).
ZK: Minutes to hours (once proof posts).
EVM COMPATIBILITY
Optimistic: Near-perfect EVM equivalence.
ZK: Improving, but some opcodes differ.
ZK: Improving, but some opcodes differ.