Across Protocol

1. Intent-Based Architecture Pioneer: Sub-Second Relayer Liquidity Fronting

1.1 Intent-Driven Bridging Archetype and Speed Benchmark

Within Ethereum Layer 2 and optimistic rollup ecosystems, traditional bridge settlement logic has historically been bottlenecked by underlying chain finality:

• The 7-Day Rollup Challenge Window Bottleneck: Under standard Optimistic Rollup cryptographic mechanisms, withdrawing assets from Arbitrum, Optimism, or Base back to Ethereum Mainnet via official canonical bridges forces users to endure a mandatory 7-day fraud-proof challenge period, alongside paying expensive L1 gas to execute a manual claim, severely impairing capital turnover efficiency.
• Across Protocol's Revolutionary Paradigm: Incubated and launched in 2021 by decentralized finance research arm Risk Labs (the core team behind the UMA protocol), Across Protocol pioneered the intent-based cross-chain architecture.
  • Instead of waiting for slow cross-chain consensus proofs, users broadcast a standardized "cross-chain fulfillment intent" across the network;
  • Globally distributed independent third-party liquidity relayers detect these intents off-chain in milliseconds. As soon as smart contracts lock funds on the source chain, relayers immediately front their own capital on the destination chain to fulfill the payout (Fronting Liquidity);
  • User-side asset arrival typically takes just 1 to 2 seconds (with official median network settlement measured at 1.2 seconds), transforming cross-chain transfers from agonizing tens of minutes into sub-second execution.

1.2 Institutional Settlement Volume & Native Uniswap Integration

Across is no experimental prototype; it is a battle-tested highway executing some of the largest on-chain liquidity flows:

• $39B+ Cumulative Cleared Volume: As of 2025/2026, Across has securely routed over $39 billion in total cross-chain transaction volume across more than 5 million unique interacting wallets, ranking among the highest-throughput bridging infrastructures in Web3.
• Uniswap's Official Native Bridging Engine: Uniswap, the world's largest decentralized exchange, directly embeds Across into its official web and mobile applications as its core cross-chain routing provider. This provides Across with top-tier ecosystem endorsement and organic order flow.
• Deep Layer 2 Rollup Matrix: Natively supports Ethereum Mainnet, Arbitrum, Optimism, Base, Polygon, zkSync, Linea, Scroll, Unichain, Soneium, World Chain, and over 20 leading networks, forming a robust liquidity superhighway across the EVM ecosystem.

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2. Full-Stack Fee Breakdown: Dynamic Capital Pricing, Relayer Gas, and Zero Platform Markup

2.1 Dynamic Capital Pricing and Relayer Cost Structure

Bridging fees on Across are calculated algorithmically in real time via an efficient game-theoretic model, featuring transparent on-chain pricing:

Total Bridging Fee = Destination Gas Reimbursed to Relayer + Dynamic Capital Utilization Fee

1. Relayer Gas Fee:
   • The native gas incurred by the relayer when executing liquidity disbursement on the target network. Following Ethereum's Dencun upgrade and blob data expansion, execution gas on major L2s has dropped to cents, making relayer execution costs negligible.
2. Dynamic Capital Fee:
   • Calculated based on the real-time liquidity utilization rate across the Ethereum Mainnet central pool (HubPool) and branch pools (SpokePools):
     • Balanced Liquidity: When capital flows are bidirectional, the capital fee drops to minimal levels, typically between 0.02% and 0.05%, delivering near-zero slippage on large stablecoin transfers;
     • Asymmetric Liquidity: When heavy directional capital surges from an L2 back to Mainnet, depleting destination reserves, the fee smoothly scales upward, incentivizing external relayers and arbitrageurs to balance reserves across chains.
3. 0% Platform Markup:
   • The Across frontend adds zero intermediary commission, protocol surcharge, or platform fee. The displayed quote reflects the pure net payout after factoring in market-maker capital costs and network execution gas.

2.2 Arbitrage Disruption Against 7-Day Canonical Bridges

• Withdrawing funds from Arbitrum, Base, or Optimism to Ethereum Mainnet via official bridges requires waiting 7 full days, followed by spending $5 to $20 in mainnet gas fees for manual claims.
• Routing through Across Protocol delivers 100% native assets to the destination mainnet address in under one minute for just a few dollars in composite relayer costs, eliminating 7-day capital lockup and significant market opportunity costs.

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3. UMA Optimistic Oracle Settlement & Native Asset Security Defense

3.1 Game-Theoretic Settlement via UMA Optimistic Oracle

The existential failure mode of cross-chain bridges lies in fraudulent verification. Rejecting vulnerable centralized multi-sig schemas, Across relies on Risk Labs' UMA Optimistic Oracle (OO) to anchor decentralized cryptographic settlement:

1. Front First, Batch Reimburse Later: Relayers front capital immediately on destination chains and bundle hundreds of fulfilled transaction hashes into periodic data batches, submitting reimbursement proposals to the HubPool on Ethereum Mainnet every few hours.
2. Economic Bonding & The Liveness Dispute Window:
   • When submitting a reimbursement claim, relayers must post a substantial token bond;
   • The UMA Optimistic Oracle enforces a challenge period (typically a 2-hour liveness window). Independent watchtowers and verification nodes continuously monitor and audit proposed payout data;
3. Severe Slashing Penalties:
   • If a relayer submits fraudulent transaction hashes to siphon funds, any observer can dispute the claim. UMA's decentralized contract arbitrates the dispute and slashes 100% of the dishonest relayer's posted bond, rewarding the challenger with a significant bounty;
   • The economic cost of fraud vastly exceeds any potential illicit gain, making honest execution the only viable equilibrium.

3.2 Impeccable Zero-Exploit History & Canonical Native Delivery

• Zero Hacks Across Multiple Market Cycles:
  • Throughout Web3 history, where cross-chain bridges suffered billions in exploit losses, Across's central HubPool has maintained an unblemished record with zero smart contract vulnerabilities or security breaches.
• 100% Canonical Native Assets:
  • Eliminates the de-pegging risks inherent in legacy bridges that mint wrapped synthetic representations (e.g., AnyUSDC).
  • Users exclusively receive canonical native tokens (such as native ETH, Circle CCTP-backed native USDC, USDT, and WBTC) on destination networks, guaranteeing maximum composability and absolute liquidity retention.

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4. Mechanism Boundaries & Operational Nuances: Asset Whitelisting, Gas Reserves, and Congestion

4.1 Focused Blue-Chip Coverage: Zero Long-Tail Asset Support

To maximize capital efficiency and protect relayer balance sheets, Across enforces a disciplined blue-chip asset policy:

• Restricted to High-Liquidity Blue Chips:
  • The protocol exclusively bridges blue-chip assets (ETH, WETH, USDC, USDT, WBTC, DAI, and governance ACX), explicitly excluding long-tail illiquid altcoins, microcap meme tokens, and unverified contracts.
  • While restricting niche trades, this focus concentrates relayer depth, allowing whale transfers worth hundreds of thousands of dollars to execute in seconds with virtually zero slippage.
• Destination Gas Self-Sufficiency:
  • Across focuses on single-token high-efficiency transfers and does not automatically bundle gas swaps. Users must ensure destination addresses maintain a small reserve of native gas tokens (e.g., small amounts of ETH on Base) to execute subsequent on-chain transactions upon arrival.

4.2 Handling Relayer Delays During Extreme Network Spikes

During network turbulence (such as high-concurrency NFT mints or market liquidations), transient bridging delays may occur:

• Relayer Risk-Mitigation Hold:
  • If destination chain gas costs spike tenfold within seconds, relayers executing transfers at agreed fixed fees face immediate losses. Relayer algorithms may temporarily pause fulfillment for a few minutes until gas normalization;
• Absolute Capital Safety:
  • User capital remains securely locked inside the source SpokePool contract. Once network conditions stabilize, relayers complete fulfillment automatically. If an intent exceeds the maximum protocol timeout without pickup, users can reclaim 100% of their deposited principal on the source chain with a single transaction.

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5. Execution Guide & Single-Sided LP Yield: Slippage Settings, Zero-IL Pools, and Tracking

5.1 Step-by-Step Bridging & Minimum Received Protection

To ensure safe, optimal execution, follow these professional on-chain steps:

1. Verify Official URL & Connect Wallet:
   • Navigate exclusively to the official application at https://across.to/ and connect an audited Web3 wallet (such as Rabby Wallet);
2. Configure Direction & Asset Quantity:
   • Select source and destination networks (e.g., Arbitrum to Base) and choose the asset (e.g., USDC);
   • Review estimated arrival times (typically 2–5 seconds) and total deducted fees;
3. Lock Minimum Received Amount:
   • Click the settings icon to review allowed fee slippage. The interface calculates a guaranteed minimum received amount to the exact decimal, eliminating unexpected rate adjustments during market volatility;
4. Sign and Settle in Seconds:
   • Sign the authorization transaction in your wallet. Once confirmed on the source chain, native funds appear in your destination wallet within 2 to 3 seconds.

5.2 Single-Sided Liquidity Staking: Zero Impermanent Loss Yield

Beyond bridging, Across provides institutional capital allocators with an uncommon single-sided passive yield structure:

• Zero Impermanent Loss Risk:
  • Unlike dual-asset AMM pairs on Uniswap that suffer impermanent loss, Across allows users to deposit single assets (USDC or ETH) in the "Pool" tab;
• Sustainable Organic Cash Flow:
  • Deposited capital sits in the L1 HubPool, serving as the liquidity reserve for relayer settlement. 100% of dynamic capital fees generated across the protocol are distributed pro-rata to LPs, supplemented by ACX staking rewards;
  • Pools feature flexible deposits and withdrawals without mandatory lockups, providing steady yield for risk-averse DeFi allocators.

5.3 On-Chain Transfer Tracking & Developer Support

• Across History Dashboard: View transaction progress, unique transfer hashes, relayer fill statuses, and confirmation counts in real time under the "History" tab;
• Community & Fallback Support: If an unexpected network partition occurs, provide your source transaction hash in the official Across Discord support channel for core developer assistance. Automated protocol timeouts ensure assets can always be safely recovered.