Across Protocol

Across Protocol is a cross-chain bridge that moves assets between blockchain networks using an intent-based architecture. Launched in September 2021 and built by Risk Labs — the same foundation that created UMA Protocol — Across is designed to solve one of the most persistent problems in a multi-chain ecosystem: moving funds between networks quickly, cheaply, and without trust assumptions.

The Problem

Traditional cross-chain bridges force users to rely on centralized custodians, fragmented liquidity on every chain, multisignature configurations, or long finality waits. Each approach introduces either security trade-offs or poor user experience. Across was designed to eliminate those trade-offs by separating the time of a user's transfer from the time of its settlement, letting a relayer network absorb the latency on behalf of users.

How It Works

Across operates on an intent-based model with three participants: users, relayers, and liquidity providers.

When a user wants to move tokens from one chain to another, they submit a deposit specifying the origin chain, destination chain, token, amount, and the fee they are willing to pay. This deposit is recorded in a spoke pool contract on the origin chain.

Relayers — independent, permissionless actors who run off-chain software — monitor these deposit events and compete to fill them. Winning relayers immediately advance funds to the user on the destination chain from their own capital, accepting the cross-chain settlement risk in exchange for the bridge fee. This is what produces the protocol's headline speed: the user receives funds in under two seconds without waiting for cross-chain finality.

After filling a transfer, the relayer requests reimbursement from the Hub Pool, a single centralized liquidity pool on Ethereum mainnet. That reimbursement request is validated by UMA's Optimistic Oracle (OO), a dispute-based verification system that assumes data is correct unless a bonded challenger disputes it within a challenge window. Because disputes require a financial bond and losing one carries a penalty, the system creates strong economic disincentives for submitting false claims. If no dispute is raised, the relayer is repaid from Hub Pool liquidity.

Liquidity providers deposit single assets into the Hub Pool and earn a share of bridge fees proportional to pool utilization. The fee model is dynamic: it rises as utilization increases and falls when liquidity is idle, creating a market-clearing incentive for LPs to supply capital when it is most needed.

Key Features

Speed and scale: Across reports average fill times under two seconds and has processed more than $35 billion in cross-chain volume since launch across 26 or more supported chains, including Ethereum, Arbitrum, Base, Optimism, Polygon, and Solana. The protocol counts more than five million users and is integrated directly by Uniswap, MetaMask, Coinbase, Lens, and Infinex, among others. Uniswap embedded Across directly into its web interface and mobile wallet, routing all in-app bridge requests through the protocol.

Swap API: The protocol exposes a developer-facing Swap API designed for rapid integration. A single call to the /swap/approval endpoint returns executable calldata, any required token approval transactions, and gas estimates — eliminating the custom wiring logic that most bridge integrations require. The API automatically selects among four routing paths depending on the tokens involved: direct bridging for identical assets, swap-then-bridge for arbitrary origin tokens, bridge-then-swap for arbitrary destination tokens, and full swap-bridge-swap for arbitrary pairs on both ends. It also selects settlement mechanisms automatically — intent-based relayer fills for speed, Circle's CCTP V2 for large USDC transfers, and LayerZero's OFT standard for native USDT — without developer intervention.

ERC-7683: Across co-authored ERC-7683 with Uniswap, a cross-chain intents standard intended to prevent relayer fragmentation and allow any compliant protocol to route intents through a shared format. This standard now underpins Uniswap's native in-app bridging.

Chain abstraction: The protocol positions its Swap API as infrastructure for chain abstraction, where applications state the outcome they want and the system determines which network, gas token, and bridge route achieves it. The same API supports AI agents executing cross-chain actions on behalf of users.

ACX Token

Across has a governance token, ACX, with a fixed total supply of one billion tokens. The initial allocation included 250 million tokens to the Across DAO treasury, approximately 195 million to Risk Labs (with roughly 150 million vesting to the team over four years), 110 million to seed investors through a vesting structure, and the remainder to other participants.

ACX serves two primary functions: governance and incentives. Holders vote on protocol upgrades and treasury decisions through Snapshot. Liquidity providers and relayers earn ACX rewards for participating in the network.

In 2026, the Across team proposed a significant structural change: dissolving the DAO and transitioning to a U.S. C-corporation called AcrossCo. The stated rationale was that growing institutional demand for Across infrastructure had made the DAO structure a legal and operational bottlenecks — enterprise partners require enforceable contracts and clear legal counterparts. Under the proposal, ACX holders would choose between exchanging their tokens for equity in AcrossCo at a 1:1 ratio (with smaller holders participating through a no-fee special purpose vehicle) or redeeming for USDC at $0.04375, which the team described as a 25% premium to the one-month average market price. A six-month decision window was proposed. The transition requires a community governance vote with a simple majority.

Security and Audits

Across relies on two principal security layers. Smart contracts have been audited by OpenZeppelin, which also conducted separate audits of UMA's Optimistic Oracle. The OO's economic design — requiring bonds for disputes, adjudicating contested claims through UMA token holder votes, and penalizing incorrect voting — creates a human verification backstop for any challenged relay claim.

The protocol reports no user funds have been lost across more than $35 billion in bridged volume since launch.

Team and Backing

Across is built and maintained by Risk Labs, the foundation that also stewards UMA Protocol. Risk Labs was co-founded by Hart Lambur, a former interest rate trader at Goldman Sachs, and Allison Lu, a former Goldman Sachs vice president, who founded UMA in 2018. Lambur serves as CEO of Risk Labs.

Across has raised $41 million in a round led by Paradigm, with participation from Bain Capital Crypto and Coinbase Ventures.

Solana Ecosystem Fit

Across supports Solana as a bridging destination, enabling users to move USDC and USDT from EVM chains to Solana via the same intent-based mechanism used for EVM-to-EVM transfers. The protocol publishes dedicated routing guides for Solana and Hyperliquid. As Across continues expanding supported chains under its V4 upgrade — adding new networks automatically for existing integrators without code changes — Solana participation forms part of its broader multi-chain routing layer serving dApp developers building on or bridging into the Solana ecosystem.