A Validium is a type of Layer 2 (L2) scaling solution that processes transactions off-chain but uses zero-knowledge proofs (ZK-proofs), specifically ZK-SNARKs or ZK-STARKs, to post cryptographic validity proofs to a base Layer 1 (L1) blockchain like Ethereum. Unlike its close relative ZK-Rollups, Validium does not publish transaction data on-chain; instead, it relies on a committee of data availability managers or a proof-of-stake network to ensure the data is available off-chain. This design dramatically reduces gas fees and increases transaction throughput but introduces a different trust assumption regarding data availability.
LABS
Glossary
Validium
A Layer 2 scaling solution that uses validity proofs for execution but stores its transaction data off-chain, relying on a Data Availability Committee or guardians.
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definition
SCALING SOLUTION
What is Validium?
A blockchain scaling architecture that uses off-chain data availability to achieve high throughput and low transaction costs.
The core trade-off in a Validium is scalability versus data availability security. By keeping data off-chain, it avoids the L1's data storage costs, enabling potentially millions of transactions per second (TPS) and near-zero fees. However, if the off-chain data becomes unavailable due to malicious actors or technical failure, users may be unable to withdraw their assets, a scenario known as data unavailability. To mitigate this, Validium networks often employ cryptographic techniques like Data Availability Committees (DACs) or validators who must cryptographically attest to data availability, with fraud proofs or slashing mechanisms to penalize bad actors.
Validium is particularly suited for high-frequency, low-value transactions where ultimate L1-level security is less critical than cost and speed. Prime use cases include high-frequency trading (DeFi), gaming assets, and microtransactions. Projects like StarkEx (powering dYdX and Immutable X) offer a Validium mode, and Polygon Miden also explores this architecture. It represents a key point on the scaling spectrum, offering a pragmatic balance for applications that prioritize performance while maintaining cryptographic security for transaction execution.
how-it-works
SCALING MECHANISM
How Validium Works
Validium is a Layer 2 scaling solution that uses off-chain data availability to achieve high transaction throughput and low fees, while leveraging the security of the Ethereum mainnet for transaction validity.
A Validium is a type of zero-knowledge rollup (ZK-rollup) that processes transactions off-chain and posts only cryptographic validity proofs to the main Ethereum chain. Unlike Optimistic Rollups, which assume transactions are valid and have a challenge period, Validium proofs, generated using zk-SNARKs or zk-STARKs, provide immediate cryptographic certainty of correctness. The defining characteristic of Validium is its approach to data availability: instead of publishing all transaction data on-chain, it keeps this data off-chain with a committee of data availability managers or a proof-of-stake network, which significantly reduces gas costs and increases throughput.
The core operational flow involves users submitting transactions to an off-chain operator or sequencer. This operator batches thousands of transactions, computes a new state root, and generates a succinct zero-knowledge proof that attests to the validity of the state transition. Only this compact proof and the new state root are posted to the Ethereum mainnet, where a smart contract verifies it. Because the raw transaction data is not published on-chain, users must rely on the off-chain data availability layer to retrieve their data and construct proofs for withdrawing assets back to Layer 1, introducing a unique data availability assumption distinct from rollups.
This architecture offers significant advantages in throughput and cost, as the most data-intensive component is removed from the main chain. However, it introduces a different security model. While the validity of state transitions is secured by Ethereum, the availability of the underlying data is secured off-chain. If the data availability committee acts maliciously or the off-chain data becomes inaccessible, users may be unable to prove ownership of their funds, potentially leading to frozen assets. This trade-off makes Validium ideal for high-volume, low-value applications like gaming or certain DeFi use cases where absolute censorship-resistance is secondary to performance.
key-features
VALIDIUM
Key Features
Validium is a Layer 2 scaling solution that uses zero-knowledge proofs for transaction validity but stores data off-chain, offering high throughput and low fees with distinct trade-offs.
01
Off-Chain Data Availability
Unlike ZK-Rollups, Validiums store transaction data off-chain with a Data Availability Committee (DAC) or a similar proof system. This removes the data cost from the main chain, drastically reducing fees, but introduces a trust assumption that the data will remain available for users to prove ownership of their assets.
02
High Throughput & Low Fees
By moving both computation and data storage off-chain, Validiums achieve extremely high transaction throughput (potentially 10,000+ TPS) and minimal user fees. This makes them suitable for high-frequency applications like decentralized exchanges (DEXs) and gaming, where cost and speed are critical.
03
Data Availability Committee (DAC)
A core component of many Validium designs. A DAC is a set of trusted, known entities that cryptographically attest to the availability of off-chain data. Users must trust that a majority of the committee is honest and will not withhold data, which is a key security trade-off versus pure rollups.
04
Withdrawal Security & Fraud Prevention
Funds are secured by zero-knowledge validity proofs (ZK-SNARKs/STARKs) on the main chain, ensuring only valid state transitions. However, if off-chain data is withheld, users may be unable to generate proofs for withdrawals, potentially freezing funds. Some designs implement emergency exit mechanisms with timelocks to mitigate this.
05
Comparison to ZK-Rollups
The primary architectural difference is data storage:
- ZK-Rollup: Data posted on-chain (Ethereum). Higher security, moderate fees.
- Validium: Data kept off-chain. Maximum scalability, lower fees, introduces data availability risk. Hybrid models like Volition allow users to choose per-transaction between rollup (on-chain data) and validium (off-chain data) modes.
06
Use Cases & Examples
Ideal for applications where absolute lowest cost and highest speed are paramount, and users accept the data availability trade-off.
- High-volume DEXs & Payments: Immutable X, StarkEx (in Validium mode).
- Web3 Gaming & NFTs: Managing millions of micro-transactions and asset transfers.
- Private Transactions: Some implementations can leverage ZKPs for enhanced privacy alongside scalability.
DATA AVAILABILITY COMPARISON
Validium vs. zkRollup: Core Differences
A technical comparison of two leading zero-knowledge scaling solutions, focusing on their core architectural trade-offs.
| Feature | Validium | zkRollup |
|---|---|---|
Data Availability Layer | Off-chain (Data Availability Committee or PoS Guardians) | On-chain (Ethereum L1) |
Data Publishing | Proofs only; transaction data kept private | Proofs and compressed transaction data |
Withdrawal Security | Depends on committee honesty; fraud proofs possible | Cryptographically secured by L1; trustless |
Throughput (TPS) | Very High (10k+) | High (2k+) |
Transaction Cost | Very Low (data cost eliminated) | Low (compressed data cost on L1) |
Censorship Resistance | Potentially lower (committee-dependent) | Inherits Ethereum's censorship resistance |
Capital Efficiency | High (no L1 data fees for liquidity) | High (fast, trustless withdrawals) |
Example Implementations | StarkEx, Polygon Avail | zkSync Era, Starknet, Scroll |
examples
SCALING SOLUTIONS
Validium Implementations & Examples
Validium is a Layer 2 scaling architecture that combines off-chain computation with data availability guarantees via a committee or proof-of-stake network. These are prominent projects implementing the model.
04
Data Availability Committee (DAC)
A core component of many validium designs, a DAC is a set of trusted entities that sign off on the availability of off-chain transaction data.
- Role: Members store data and provide attestations; if a majority is honest, data can be reconstructed.
- Trust Assumption: Introduces a weak subjectivity or crypto-economic trust layer compared to on-chain data.
- Examples: StarkEx uses a DAC of known organizations; other models use proof-of-stake validators as guardians.
05
Volition: The Hybrid Model
A system, pioneered by StarkWare, that gives users or applications a choice per transaction between ZK-rollup and validium data availability.
- Mechanism: Users select whether their transaction data is posted on-chain (rollup, higher security/cost) or held off-chain by a DAC (validium, lower cost).
- Flexibility: Allows asset-specific or use-case-specific security models within a single application.
- Adoption: Central to the design of StarkEx and Polygon Miden.
06
Key Trade-off: Security vs. Throughput
Validium implementations optimize for throughput and cost by moving data off-chain, which introduces a distinct security consideration compared to rollups.
- Security: Relies on the honesty of the Data Availability Committee or Guardian network. Malicious collusion could freeze funds, but cannot create invalid state due to ZK proofs.
- Throughput: Unconstrained by Ethereum's gas limits for data, enabling ~10k-20k+ TPS.
- Use Case Fit: Ideal for high-frequency trading (dYdX), gaming (ImmutableX), and applications where ultimate Ethereum-level security is not required for every action.
security-considerations
VALIDIUM
Security Considerations & Trade-offs
Validium is a Layer 2 scaling solution that uses zero-knowledge proofs for validity but stores data off-chain, creating a distinct security model compared to rollups.
01
Data Availability Risk
The primary security trade-off. Transaction data is stored off-chain by a Data Availability Committee (DAC) or a Proof-of-Stake (PoS) network, not on the base layer (e.g., Ethereum). This creates a data availability problem: if the committee acts maliciously or the off-chain storage fails, users may be unable to prove ownership of their assets and withdraw them, potentially leading to frozen funds.
- DAC-based: Relies on a permissioned set of trusted entities.
- PoS-based: Uses a decentralized network of stakers, but still off-chain.
02
Withdrawal Security & Exit Games
Users can withdraw assets to Layer 1 via a fraud proof or validity proof mechanism, but the process is contingent on data availability. If data is withheld, a mass exit may be triggered. However, without the data to construct Merkle proofs, users cannot participate in the exit, rendering the mechanism ineffective. This contrasts with zk-Rollups, where on-chain data guarantees the ability to exit.
03
Censorship Resistance
The off-chain sequencer (which orders transactions) and the Data Availability providers have the potential to censor transactions. While users can force transactions via Layer 1, this requires the disputed data to be available. Validium typically offers lower censorship resistance than Rollups, where transaction data is publicly posted on-chain, allowing anyone to reconstruct state and challenge censorship.
04
Throughput vs. Security Spectrum
Validium represents a point on the scaling spectrum prioritizing ultra-high throughput and low cost over base-layer security guarantees.
- Higher Throughput: No gas costs for posting data to Layer 1.
- Lower Fees: Users pay only for proof verification, not calldata.
- Trade-off: Accepts the trust assumption or cryptoeconomic security of the off-chain data layer instead of Ethereum's full security. It is less secure than a zk-Rollup but more secure than a pure sidechain.
05
Real-World Implementations
Examples illustrate the security model choices:
- StarkEx (Validium Mode): Used by dYdX and Immutable X, employs a permissioned Data Availability Committee.
- zkPorter (Ethereum): A proposed Validium for zkSync using a Proof-of-Stake network for data availability.
- Polygon zkEVM Validium: Offers a configurable data availability layer, allowing applications to choose between zk-Rollup and Validium modes.
06
Comparison with zk-Rollup
The key distinction lies in data availability location, which dictates security and cost.
| Aspect | Validium | zk-Rollup |
|---|---|---|
| Data Storage | Off-Chain | On-Chain (Ethereum) |
| Security Guarantee | Dependent on off-chain layer | Inherits Ethereum's security |
| Transaction Cost | Very Low | Low (calldata cost) |
| Withdrawal Safety | Conditional on data availability | Unconditionally secure |
Validium is chosen for applications where extreme scalability is paramount and users accept alternative trust models.
benefits-tradeoffs
VALIDIUM
Benefits and Trade-offs
Validium is a Layer 2 scaling solution that processes transactions off-chain while storing only cryptographic proofs on the main blockchain, using off-chain data availability. This architecture presents a distinct set of advantages and compromises compared to other scaling models.
01
Scalability & Low Cost
Validium achieves high throughput and minimal fees by moving computation and data storage off-chain. Transaction finality is fast, and costs are not directly tied to mainnet gas prices. This is ideal for high-frequency applications like gaming or decentralized exchanges.
- High TPS: Can process thousands of transactions per second.
- Low Fees: Users pay only for proof verification on-chain.
- Example: dYdX v3 operated as a Validium, enabling near-instant, feeless trading.
02
Enhanced Privacy
Because data is kept off-chain, Validium can offer stronger privacy guarantees than typical rollups. Transaction details are not publicly posted on the base layer, visible only to the operator and participants. This enables use cases requiring confidentiality.
- Data Confidentiality: Sensitive transaction data remains off the public ledger.
- Selective Disclosure: Users can prove transaction validity without revealing details.
03
Data Availability Risk
The core trade-off of Validium is off-chain data availability. Users rely on a committee of Data Availability Committee (DAC) members or a proof-of-stake network to store and provide transaction data upon request. If this data becomes unavailable, users may be unable to withdraw their assets.
- Trust Assumption: Requires trust in the DAC's honesty and operational security.
- Censorship Risk: A malicious DAC could withhold data, freezing funds.
04
Security vs. Optimistic/ZK Rollups
Validium uses ZK-SNARKs for cryptographic security like a ZK-Rollup, but its security model differs due to data availability.
- Vs. ZK-Rollup: A ZK-Rollup posts data on-chain, inheriting Ethereum's full security for data availability. Validium trades this for greater scalability.
- Vs. Optimistic Rollup: Both have off-chain execution, but Optimistic Rollups have on-chain data and a 7-day fraud proof challenge period. Validium has instant finality via proofs but off-chain data.
05
Withdrawal Challenges
The withdrawal process in a Validium can be more complex than in a rollup. To withdraw funds to Layer 1, a user must provide a Merkle proof of ownership. If the off-chain data is unavailable, the user cannot generate this proof, potentially locking funds. Some implementations use escape hatches or forced trade mechanisms as a last resort.
- Proof Requirement: Requires access to the latest state root and your transaction data.
- Mitigation: DACs are incentivized and often staked to remain available.
06
Use Cases & Examples
Validium is suited for applications where extreme scalability and low cost are paramount, and users accept the data availability trade-off.
- High-Volume DEXs: Platforms requiring massive order book throughput.
- Privacy-Focused Apps: Financial or enterprise applications needing data confidentiality.
- Gaming & Social: Microtransactions and frequent state updates.
- Real Implementations: StarkEx (by StarkWare) offers a Validium mode, used by platforms like Immutable X and Sorare.
VALIDIUM
Frequently Asked Questions
A deep dive into Validium, a Layer 2 scaling solution that prioritizes high throughput and low cost by keeping data off-chain while securing transactions with validity proofs.
Validium is a Layer 2 scaling solution that processes transactions off-chain and uses validity proofs (like ZK-SNARKs or ZK-STARKs) to guarantee their correctness, but unlike zk-Rollups, it does not publish transaction data to the main Ethereum chain. It works by having a prover generate a cryptographic proof that a batch of transactions is valid according to the rules of the Virtual Machine. This proof is posted to Layer 1 for verification, while the actual transaction data is stored off-chain by a committee or Data Availability Committee (DAC). This separation allows for extremely high throughput and low fees, but introduces a data availability assumption, meaning users must trust that the committee will provide the data if needed to reconstruct the state.
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