Across: Making Bridging Fast & Cheap

This week we’re highlighting Across, which is enabling fast and cheap token flows between chains with its intent-based model. You can now claim your share of ACX in Fluidkey.

If you have ever bridged tokens between two chains on Fluidkey, chances are high that this action was powered by Across. So how does Across’ intent-based model work?

Everything starts with an intent, e.g. “I want to move 100 USDC from Arbitrum to Base”.

Once this intent is submitted to Across, so-called relayers compete to fulfil this intent at the lowest cost and fastest speed possible. This results in a quote showing how much the bridging action will cost and how long it will take.

The user then confirms the quote and deposits the 100 USDC in the escrow contract on Arbitrum. As soon as this is done, the relayer will deposit 100 USDC on the user’s destination address on Base.

Now the relayer can submit proof of the completed transfer to UMA’s Optimistic Oracle. This system optimistically assumes the transfer was valid. If no one disputes this proof within a short challenge period, the relayer is automatically refunded from the 100 USDC in the escrow contract. This 1-of-N security model means only a single honest observer is needed to keep the entire system secure.

To dive deeper, this explainer as well as this ETH Denver talk by Nicholas Pai from Across are good resources.

Across recently unveiled its v4, which replaces the former hub-and-spoke model with a universal design that uses ZK proofs, in partnership with Succinct, to verify transactions. This allows for permissionless expansion to new chains without needing custom code or long audits for each integration.

Across’ token, ACX, plays two major roles: it is Across’ governance token and is also used to reward key participants in the ecosystem, such as liquidity providers and relayers, for their contributions.

Bridging has drastically improved over the past few years, from taking +10 minutes and significant costs to now being close to instant and costing just a few cents, and Across played an important role here. We’re excited to follow along as they keep pushing the boundaries of cross-chain interop.

Note that none of our highlights are financial advice. The value of any of the tokens highlighted may go to zero.

See you next week!