Across Protocol
Executive Summary
The fastest credible way to move major assets between EVM L2s. Across uses bonded relayers who front you the destination asset in seconds, then reconcile against an optimistic oracle. Fast and cheap — at the cost of relayer and oracle assumptions.
"Across is the standout intent-based bridge for the EVM L2 ecosystem — fast, cheap, and capital-efficient, with a design that sidesteps the wrapped-asset honeypots behind most historical bridge exploits."
Key Advantages
- ✓Intent-based design delivers near-instant settlement — major assets typically arrive in seconds
- ✓Single unified liquidity pool avoids the fragmented wrapped-asset honeypots that plague lock-and-mint bridges
- ✓Relayers front their own capital and bear the finality risk, not the user
- ✓Consistently among the lowest-fee routes for EVM L2-to-L2 transfers
- ✓Often the underlying route selected by bridge aggregators — a strong signal of competitive pricing
Major Trade-offs
- ×Security ultimately rests on UMA's Optimistic Oracle and its dispute mechanism — a different trust assumption than canonical bridges
- ×EVM-only: no Solana, Aptos, or other non-EVM coverage, unlike Wormhole
- ×Relayer network must remain competitive and capitalized for quotes to stay fast and cheap
- ×Intents/optimistic-oracle model is harder for non-technical users to reason about than a simple lock-and-mint bridge
Bridge to Any Chain
Multi-hop bridging across 20+ chains. Best route, best rate, fully non-custodial.
/ Operational Metrics
| Network Architecture | EVM L2s + Ethereum (Arbitrum, Optimism, Base, Polygon, zkSync, and more) |
| Native Token | ACX |
| KYC Requirement | No KYC (Permissionless) |
| Total Value Locked | N/A |
| 24h Volume | N/A |
/ Architecture & Mechanics
Across is an intents-based bridge built around a single unified liquidity pool and a network of competitive relayers. When you bridge, you sign an intent — "I want X on the destination chain" — and a relayer immediately fronts you that asset out of their own inventory, usually within seconds. The relayer is later reimbursed from Across's hub pool on Ethereum once the deposit is verified by UMA's Optimistic Oracle. This design means users get near-instant settlement without waiting for canonical finality, while the heavy capital sits in one audited pool rather than fragmented across dozens of wrapped-asset honeypots. Across consistently ranks among the cheapest and fastest bridges for EVM L2-to-L2 transfers, which is why it is frequently the route that bridge aggregators select under the hood.
Across separates fast settlement from slow verification. A user deposits on the source chain and signs an intent for the asset they want on the destination chain. A competitive relayer immediately fulfills that intent from their own inventory, giving the user near-instant settlement. The relayer then submits a claim for reimbursement from the hub pool on Ethereum; UMA's Optimistic Oracle verifies the original deposit during a liveness window, and if unchallenged, the relayer is repaid from the unified pool. This lets users avoid waiting for canonical finality while keeping liquidity consolidated and capital-efficient.
/ Fee Schedule
Relayer Fee
Dynamic, set by relayer competition — typically a few basis points on major routes
LP Fee
Small fee paid to hub-pool liquidity providers, scales with pool utilization
Destination Gas
Standard destination-chain gas, often bundled into the quote
/ Threat Matrix
Vector
Optimistic Oracle Dispute
Severity
Analysis
Deposit verification relies on UMA's Optimistic Oracle. A successful manipulation of the dispute/liveness mechanism could allow invalid repayments from the hub pool. The economic security depends on honest disputers being incentivized to challenge bad assertions within the liveness window.
Vector
Hub Pool Smart Contract
Severity
Analysis
All bridged liquidity is concentrated in a single hub pool on Ethereum. While this avoids wrapped-asset fragmentation, a contract bug in the hub pool would be high-impact. The contracts are audited, but the concentration is itself a consideration.
Vector
Relayer Liveness
Severity
Analysis
If relayers are unavailable or under-capitalized, transfers fall back to slower settlement against the pool rather than failing — a degradation of UX rather than a loss of funds, but worth understanding.
Regulatory & Legal Caveats
As with all cross-chain bridges, Across moves value across networks without built-in AML controls, which is an area of increasing regulatory attention. The protocol is governed by the Across DAO and the ACX token, which carries standard governance-token securities scrutiny in the US. Because relayers are independent actors fronting their own capital, the regulatory characterization of their role is less settled than that of a custodial bridge operator. Frontend access may be geofenced in some jurisdictions.
Target Demographic
DeFi users moving major assets between EVM L2s who want the fastest, cheapest credible route and don't need non-EVM coverage. Users comfortable with an intents/optimistic-oracle trust model rather than a canonical bridge's longer-but-stronger guarantee. Anyone who has used a bridge aggregator has likely been routed through Across without realizing it.
/ Execution Protocol
Open the Across app
Go to across.to and connect your EVM wallet (MetaMask, Rabby, or any WalletConnect-compatible wallet). Across is EVM-only, so both source and destination must be supported EVM chains or L2s.
Select route and asset
Choose the source chain, destination chain, and the asset you want to move. Across quotes a single all-in price including relayer and LP fees — review it before confirming. For major assets on popular L2 routes the quote and ETA update in real time.
Sign the intent and deposit
Approve the token if needed, then confirm the deposit transaction on the source chain. Once your deposit is seen, a relayer fronts the destination asset — for major routes this typically completes within seconds, well before canonical finality.
Verify receipt
Confirm the asset has arrived in your destination wallet. Across delivers the native or canonical asset rather than a bespoke wrapped variant on supported routes. If a relayer doesn't pick up the intent, the transfer settles more slowly against the hub pool — check the Across explorer for status.
/ Alternatives to Across Protocol
LayerZero
8The dominant cross-chain messaging standard. Most users never interact with LayerZero directly — they use the dozens of apps built on top of it without knowing it. That's what becoming infrastructure looks like.
Wormhole
7.8The most important bridge you've probably never thought about. If you've moved money between Ethereum and Solana, you've used Wormhole. The 2022 hack — fully repaid by Jump — remains the elephant in the room.
How Protocol Signal Reviews Work
First-hand testing
Every protocol is actively used by our analysts with real on-chain capital before review.
Exploit history disclosed
We name every historical exploit, audit gap, and oracle risk — not just the marketing talking points.
Canonical links only
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Final Verdict
"Across is the standout intent-based bridge for the EVM L2 ecosystem — fast, cheap, and capital-efficient, with a design that sidesteps the wrapped-asset honeypots behind most historical bridge exploits. The trade-off is a trust model anchored in UMA's Optimistic Oracle rather than canonical security, which is a reasonable assumption for routine L2 transfers but worth weighing for very large, non-urgent moves to Ethereum mainnet. For everyday cross-L2 transfers, it is one of the strongest options available — and the frequency with which aggregators route through it is the clearest endorsement of its pricing."
Frequently Asked Questions
How is Across different from a normal lock-and-mint bridge?
Lock-and-mint bridges lock your asset on the source chain and mint a wrapped version on the destination, concentrating risk in large wrapped-asset pools. Across instead has a relayer front you the real destination asset from their own inventory in seconds, then reimburses that relayer from a single unified pool after an optimistic-oracle verification. You get native assets, faster settlement, and no wrapped honeypots.
What is the optimistic oracle and why does it matter?
Across uses UMA's Optimistic Oracle to verify that a deposit actually happened before reimbursing the relayer who fronted the funds. Assertions are assumed true unless challenged within a liveness window, and honest disputers are economically incentivized to challenge false ones. This is the core of Across's security model — different from a canonical bridge that inherits the chain's own security.
Is Across safe for large transfers?
For routine EVM L2-to-L2 transfers, Across's track record and consolidated-pool design make it one of the safer fast bridges. For very large, non-urgent transfers to Ethereum mainnet where you can tolerate the wait, a canonical bridge offers a stronger guarantee. As with any bridge, don't leave funds parked — transfer and move on.
Why do bridge aggregators route through Across so often?
Because it is frequently the cheapest and fastest route for major EVM L2 pairs. Aggregators quote multiple underlying bridges and pick the best execution; Across's relayer competition and capital efficiency mean it regularly wins those auctions, which is a strong third-party signal of its pricing.
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