August 11, 2026 · 5 min read
Rollup vs Validium vs Optimium: Where Your L2's Data Actually Lives
L2s differ on two independent axes: how they prove state (validity/ZK proofs vs fraud proofs) and where they put data availability (on Ethereum vs off-chain). Those two choices give you rollups, validiums, and optimiums — with real differences in cost, security, and worst-case fund recovery. Here's the taxonomy, plainly, and why it matters for developers.
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