Hop vs Across: Fee Efficiency

Hop Protocol excels at optimizing for speed and predictable, low-cost transfers between major Layer 2 rollups (Arbitrum, Optimism, Base) because it utilizes a canonical token bridge and a network of automated market makers (AMMs) on each destination chain. For example, a transfer from Arbitrum to Optimism often completes in minutes with fees typically under a few dollars, as it's a liquidity-based model where the finality of the source chain (e.g., Arbitrum's ~1 minute) is the primary bottleneck.

Across Protocol takes a different approach by employing a single, unified liquidity pool on Ethereum mainnet and a network of off-chain relayers who compete to fulfill user requests. This results in a critical trade-off: while users often see lower net costs for long-tail or high-value transfers due to intense relayer competition and efficient capital utilization, they must wait for the source chain's challenge period (e.g., ~12 minutes for Optimism, ~7 days for Arbitrum) for full economic security, introducing a latency-for-costs trade-off.

The key trade-off: If your priority is deterministic, fast finality for frequent, lower-value transfers between established L2s, choose Hop. Its AMM-based model is optimized for the rollup ecosystem. If you prioritize absolute fee minimization for high-value or cross-ecosystem transfers (e.g., Polygon to Arbitrum) and can tolerate variable latency, choose Across. Its single-pool, relayer-based architecture often wins on pure cost for non-time-sensitive moves.

Hop Protocol excels at predictable, low-cost transfers for high-volume users and integrators because of its native AMM-based model. By leveraging liquidity pools on destination chains, Hop provides a clear, upfront fee quote that includes a small protocol fee (e.g., 3-5 bps) and the destination chain's gas cost. This model is highly efficient for frequent, large transfers where fee predictability is critical, as seen in its integration with protocols like Connext and Socket for optimized routing.

Across Protocol takes a different approach by utilizing a competitive, auction-based relay system. This results in a trade-off between potential for lower absolute costs and less fee predictability. Relayers bid to fulfill transfers, often leading to lower realized fees for users, especially during non-peak times. However, fees can be more variable. This model is powered by UMA's optimistic oracle and a single liquidity pool on Ethereum, making it highly capital-efficient for the protocol but introducing a variable cost for the end-user.

The key trade-off: If your priority is cost predictability and integration simplicity for high-frequency operations, choose Hop. Its AMM model offers stable, composable fees ideal for dApps and bots. If you prioritize achieving the lowest possible absolute transfer cost and can tolerate some fee variability, choose Across. Its relay auction can provide superior fee efficiency for less time-sensitive, larger transactions where users can afford to wait for the best bid.