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What is a validium?
A validium is a layer 2 network that proves its transactions correct with zero-knowledge validity proofs, like a zk-rollup, but keeps the transaction data off the main chain instead of publishing it there. That makes it cheaper and faster, at the cost of depending on whoever holds the data.
What it means for you
Your funds in a validium are only as reachable as its data. If the data managers withhold it, you cannot build the proof needed to withdraw, and funds can be frozen even though no one can forge transactions. Check who holds the data and whether the network is a rollup or a validium; the difference decides how you exit.
A common mistake: “A validium uses zero-knowledge proofs, so it is as secure as a zk-rollup.”
In fact: The proofs stop invalid transactions, but they do not keep the data available. If the off-chain data is withheld, users cannot prove their balances to withdraw, a risk a zk-rollup avoids by posting data to Ethereum.
How it works
Like a zk-rollup, a validium executes transactions off chain and posts a validity proof (a zk-SNARK or zk-STARK) to a contract on Ethereum, so invalid state cannot be accepted. Unlike a rollup, the transaction data stays off chain, often with a data availability committee: a group of entities that store it and attest that it is available. Withdrawing needs a Merkle proof of your balance built from that data, so a committee that is compromised and withholds it can block exits. Volitions combine both, letting users switch between validium and rollup data modes.
Sources: ethereum.org: Validium, ethereum.org: Data availability · checked 4 October 2026
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