⚖️ Optimistic vs ZK: Choose Your Rollup

Compare fraud proofs vs validity proofs in Layer 2 scaling

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Introduction

⚖️ Optimistic vs ZK Rollups

Rollups are the leading Layer 2 scaling solution for Ethereum, but they come in two fundamentally different flavors: Optimistic and ZK. Understanding their core differences is crucial for choosing the right scaling approach.

🎯 The Core Difference

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Optimistic Rollups

"Innocent until proven guilty"

Transactions are assumed valid by default. Anyone can challenge suspicious transactions during a 7-day dispute period using fraud proofs.

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ZK Rollups

"Prove you're right upfront"

Every transaction batch includes a cryptographic proof (validity proof) that mathematically guarantees correctness before acceptance.

🎮 Interactive Rollup Explorer

Select a rollup type to explore its characteristics, trade-offs, and real-world implementations.

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Optimistic Rollups

Approach

Assume Valid, Challenge if Wrong

Security Model

Fraud Proofs (reactive)

Withdrawal Time

7 days

Key Feature

Transactions are assumed valid unless challenged during dispute period

✓ Advantages

• EVM compatibility
• Lower computational cost
• Simpler to implement

✗ Trade-offs

• Long withdrawal delays
• Relies on watchers
• Higher data costs

Popular Implementations

ArbitrumOptimismBase

🤔 Why Two Approaches?

Both rollup types solve the same problem (Ethereum scaling) but make different trade-offs:

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Speed vs Security: Optimistic rollups are faster to execute but slower to finalize. ZK rollups take longer to prove but finalize instantly.

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Cost Trade-offs: Optimistic rollups have cheaper execution but higher data costs. ZK rollups have expensive proving but cheaper data posting.

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Complexity: Optimistic rollups are simpler and more EVM-compatible. ZK rollups require complex cryptography but offer stronger guarantees.