Across Protocol Review 2026: Fees, Speed & How It Works

Across Protocol has become one of the most widely recommended bridges in 2026, and the reason is a deliberately different architecture: relayers front your funds on the destination chain instead of making you wait for cross-chain verification. This review explains how Across actually works, what you pay, how it stays secure, and when you might prefer a different bridge.

What Is Across Protocol?

Across Protocol is an intent-based cross-chain bridge built on Ethereum. It was developed by the Risk Labs team (the same team behind the UMA Protocol optimistic oracle) and launched in late 2021. It currently supports transfers between Ethereum mainnet and all major L2 networks.

The fundamental difference from liquidity-pool bridges (like Hop or Stargate) is that Across uses relayers rather than shared liquidity pools on each chain. Understanding this distinction explains how Across works and what its fees pay for.

How Across Works: Intent-Based Architecture

When you initiate a bridge transfer on Across, this is the sequence of events:

You deposit tokens into the Across contract on the source chain and specify your destination
A relayer detects your deposit, fronts the equivalent amount from their own capital on the destination chain, and sends it to you immediately
UMA’s optimistic oracle verifies that the relayer correctly fulfilled the transfer (a short dispute window applies)
The relayer is reimbursed from Across’s canonical liquidity pool on Ethereum, plus the fee you paid

The key insight: you receive funds on the destination chain within minutes of the relayer’s action — you do not wait for the full verification process. The oracle dispute window only affects relayer reimbursement, not your delivery. Across’s docs give no typical fill time; its API returns an estimated fill time with each quote.

See also: How Cross-Chain Bridges Work for a broader explanation of bridge architectures.

Across Fee Structure

The Across fee documentation defines the total fee as the difference between what you deposit and what you receive. It is made up of these parts, plus the gas you pay yourself:

1. LP Fee (Liquidity Provider Fee)

This fee goes to liquidity providers and compensates them for capital utilization and rebalancing risk. It is dynamic: it depends on how much of the pool is currently in use. Across publishes no typical rate.

2. Relayer Fee

This fee goes to the relayer who fills your transfer. It covers the relayer’s gas costs, the opportunity cost of the capital they front, and their risk. On routes with expensive destination gas, expect it to be higher.

App Fee (optional)

Apps built on Across can add their own fee on top. If you bridge through a wallet or dApp rather than across.to, check whether it does.

3. Gas Fee

You pay gas on the source chain to initiate the deposit transaction. On Ethereum mainnet, this is the dominant cost for small transfers. On L2 sources (Arbitrum, Optimism, Base), gas is negligible. Across minimizes on-chain steps to reduce gas relative to multi-step bridges. See Best Time to Bridge Crypto for gas timing optimization.

Across’s docs give no typical total, and they tell integrators not to cache fee responses because fees change with conditions. The total for a route like USDC from Arbitrum to Ethereum therefore only shows up in a live quote.

For the short version, see the Across Protocol bridge fees overview, a one-page summary based on the provider's official docs.

→ Compare real-time bridge fees on BridgeFees.com — no wallet needed

Supported Chains and Tokens

As of 2026, Across supports transfers between:

Ethereum mainnet (source and destination)
Arbitrum One and Arbitrum Nova
Optimism and OP Stack chains (Base, Mode, Blast)
Polygon PoS
zkSync Era
Linea
Scroll

Supported tokens include ETH, WETH, USDC, USDT, DAI, WBTC, and several other major assets. Across focuses on high-quality liquidity for a curated set of tokens rather than supporting every long-tail asset. For multi-chain stablecoin transfers, see USDT bridging guide and DAI bridging guide.

Speed: How Fast Is Across?

Across’s current docs publish no typical fill times. Relayers lock their own capital to fill intents immediately, and the Across API returns an estimated fill time with each quote, whether you are bridging ETH from Arbitrum to Base or using the Ethereum → Optimism ETH route.

For context, the native Arbitrum or Optimism bridge for L2→L1 withdrawals takes 7 days due to the optimistic challenge period. Across — by using relayers — bypasses this wait: the relayer is reimbursed later through Across’s settlement process, while you receive the funds as soon as the relayer fills your transfer.

Security Model

Across uses UMA’s optimistic oracle for verification. This means:

Transfers are assumed valid by default
Anyone can dispute a transfer within the challenge window
Disputes are settled by UMA’s decentralized verification mechanism using economic incentives
The smart contracts on each chain have been audited multiple times

The security assumption is that at least one honest participant will challenge fraudulent relayer behavior during the dispute window. In practice, Across runs its own monitoring bots and the relayer network is permissioned for larger amounts to reduce fraud risk.

For a comprehensive bridge security analysis, see Crypto Bridge Security Guide.

When to Use Across vs. Alternatives

Choose Across when:

Transferring ETH, USDC, USDT, or DAI on any supported route
You want the fastest L2→Ethereum withdrawal without waiting 7 days
Its quote for your route and amount is the lowest in a live comparison

Consider alternatives when:

You need a chain not yet supported by Across (use LI.FI or Synapse)
You are bridging very large amounts where relayer capital may be limited and Stargate’s unified liquidity is worth comparing
You need a token not in Across’s supported list
You want an AMM-based bridge for reasons of decentralization philosophy (note that Hop Protocol’s quote API stopped responding in July 2026)

Across vs. Hop vs. Stargate: Quick Comparison

See the full breakdown in Stargate vs. Hop vs. Across Comparison. In summary:

Across: LP fee plus relayer fee, relayers fill immediately; built for standard EVM L2 routes such as Ethereum to Base USDC
Hop: AMM-based bonder model; its quote API stopped responding in July 2026, so BridgeFees.com no longer compares it
Stargate: Dynamic V2 fee plus LayerZero messaging fee, unified liquidity, wider chain/token support

BridgeFees.com and Across

BridgeFees.com queries Across in real time alongside other bridge providers. Because BridgeFees.com shows the complete cost breakdown (protocol fee + gas estimate), you can see exactly how Across compares for your specific amount, token, and route without needing to connect a wallet.

Frequently Asked Questions

What is the Across Protocol LP fee and how does it change?

The LP fee compensates liquidity providers in Across’s capital pool for capital utilization and rebalancing risk. It is dynamic and depends on how much of the pool is in use. Across’s docs publish no typical rate and ask integrators not to cache fee responses, so the current fee only shows up in a live quote, for example on BridgeFees.com.

Is Across safe? Has it been hacked?

Across has not experienced a significant exploit as of mid-2026. The contracts have been audited by multiple security firms. The UMA optimistic oracle mechanism has also operated without a successful exploit. No bridge is risk-free, but Across has a strong security track record relative to peers.

Can I bridge large amounts through Across?

Yes, but very large amounts depend on relayers having enough capital on the destination chain. The relayer fee covers the relayer’s capital cost and risk, so it can rise with size, and you may need to split the transfer. For large transfers, compare the quote against Stargate’s unified liquidity pools.

Does Across support non-EVM chains?

No. As of 2026, Across is EVM-only. For Solana, Cosmos, or other non-EVM transfers, you need a different bridge (Wormhole, IBC, etc.).

How does Across compare to the native Arbitrum/Optimism bridge?

Across is almost always better for L2→Ethereum transfers. The native bridge has a 7-day withdrawal window for optimistic rollups, while an Across relayer fronts the funds on Ethereum, so you do not wait for that window. You pay the LP fee plus the relayer fee instead. For Ethereum→L2 deposits, the native bridge charges no bridge fee, so compare it with the Across quote.

What tokens does Across support?

ETH, WETH, USDC (native and bridged variants), USDT, DAI, WBTC, and a growing list of additional assets. The token list expands as liquidity grows. Check across.to for the current supported asset list.