What is Across Protocol (ACX)?
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🟢 The simple version
Plain English — no jargon. Start here.
Across Protocol is an intent-based cross-chain bridge that achieves the fastest and cheapest bridging for most routes — users specify what they want on the destination chain, competitive "relayers" fill the order immediately from their own inventory, and the protocol batches settlement across chains to minimise costs.
Intent-based bridging — how it's different
Traditional bridges transfer your specific tokens: you deposit USDC on Arbitrum, a message is sent, and USDC is released on Optimism. Across uses "intents": you specify "I want 1000 USDC on Optimism," relayers compete to fill your order, and the fastest relayer sends 1000 USDC from their Optimism inventory immediately. The relayer is then reimbursed from your Arbitrum USDC later via Across's settlement system.
This intent model is faster and cheaper: (1) users get instant fills because relayers front capital; (2) fees are competitive because multiple relayers bid on each request; (3) settlement is batched, reducing per-transaction gas costs. Across consistently ranks among the cheapest cross-chain bridges by fee in DeFi aggregator comparisons.
UMA's Optimistic Oracle — the settlement layer
Across was built by Risk Labs, the team behind UMA Protocol (a decentralised oracle for arbitrary data disputes). Across uses UMA's Optimistic Oracle for settlement verification: when a relayer claims reimbursement for a fill, the claim is assumed valid unless disputed within the challenge window. This optimistic verification is efficient and avoids expensive on-chain proof for every transaction. In the rare case of a fraudulent claim, the UMA oracle dispute mechanism resolves it.
Is ACX legal in India?
Yes. ACX qualifies as a Virtual Digital Asset (VDA) under Indian law. 30% tax on gains and 1% TDS applies. Always consult a tax professional.
🟡 A bit more detail
For when you want to go a little deeper.
Across vs Hop vs Stargate
Across: intent-based, fastest fills for common routes, UMA optimistic settlement. Best for speed + cost on popular corridors (Arbitrum↔Optimism↔Base). Hop: AMM-based with bonders, instant hToken swap, strong for L2 ecosystem bridging. Stargate: LayerZero messaging, native asset (not wrapped), better for cross-ecosystem transfers (Ethereum to Avalanche or BNB Chain). Each has route-specific advantages — DeFi aggregators like LiFi and Socket route to the cheapest/fastest option per transfer.
ACX token and the airdrop
ACX is Across's governance token. It launched in November 2022 via a retroactive airdrop to early users. ACX governance controls: fee settings, relayer whitelist (if any), supported chains, and treasury management. The DAO has focused on maintaining deep relayer liquidity and expanding to new chains.
Across relayers front their own capital for fills. If a relayer fills a fraudulent request (e.g., a user's funds on the source chain don't actually arrive), the relayer bears the loss. UMA's dispute mechanism provides recourse, but there's a window of relayer capital exposure. Users are protected by the relayer competition model — but relayers bear operational risk. Live data: CoinGecko
🟣 The full technical picture
For the technically curious.
Key facts
- Token: ACX (governance, launched Nov 2022 airdrop)
- Function: Intent-based cross-chain bridge
- Built by: Risk Labs (UMA Protocol team)
- Settlement: UMA Optimistic Oracle
- Speed: Near-instant (relayers fill from own inventory)
- Fee model: Competitive relayer bids → typically cheapest for popular routes
- Chains: Ethereum, Arbitrum, Optimism, Base, Polygon, ZkSync, and more
- vs Hop: Intent-based vs AMM-based; Across typically cheaper for large amounts
- vs Stargate: L2-focused vs broader cross-ecosystem
Relayer competition mechanics
When you submit a bridge request on Across, your desired output (e.g., 999 USDC on Optimism, accepting up to 1 USDC fee) is broadcast to the relayer network. Relayers monitor pending requests and compete to fill them. The first relayer to fill gets the fee. Relayers use sophisticated algorithms to manage their cross-chain inventory — they maintain capital on each chain and fill requests where their inventory is deepest. The protocol then reimburses relayers from the deposited funds on the source chain, batching multiple reimbursements to reduce gas costs. This batch settlement happens hourly or when sufficient volume accumulates.