Across Protocol: Cross-Chain Bridge Fee Tracking

2026-07-14

Across is a decentralised cross-chain bridge that uses an optimistic oracle, bonded relayers, and single-sided liquidity pools to move tokens between rollups and Ethereum mainnet. Rather than requiring large two-sided liquidity pools on every chain, Across uses a single canonical pool on Ethereum and a network of relayers who front user funds on the destination chain. Relayers are reimbursed from the origin chain after a challenge window, making transfers near-instant from the user's perspective.

What makes Across unusual from a fee tracking standpoint is that the protocol retains zero revenue. Every fee generated on a bridge transaction goes entirely to the two parties who do the work: relayers who execute the transfer, and liquidity providers who supply capital to the canonical pool. The fee size is determined algorithmically based on pool utilisation: high-utilisation routes charge higher fees to attract more capital, while low-utilisation routes stay cheap.

The adapter reads FilledRelay events from Across SpokePool contracts deployed on each of more than twenty chains, including Ethereum, OP Mainnet, Arbitrum, Base, Polygon, Solana, and Robinhood Chain. The relayerFee and lpFee fields in each event give the exact fee amounts for that transfer. These are summed across all chains and converted to USD using asset prices at event time. The challenge was handling over twenty SpokePool contracts and ensuring the multi-chain aggregation was correct: a mismatch in contract addresses on any chain would silently undercount volume.

All-time fees stand at $18.9 million, with $19,300 in the past seven days and $2,000 in the most recent day. The fact that 100% of fees go to relayers and LPs rather than a treasury makes Across a fully supply-side protocol: the adapter needed to correctly classify all revenue as supply-side rather than protocol revenue, which is an important distinction for DefiLlama's analytics.

Website: across.to · Twitter: @AcrossProtocol