Onthis Shortcuts
A Shortcut allows users to execute onchain actions by sending funds to a contract address.
Each Shortcut is a unique smart contract designed to carry out the desired function. Shortcuts are represented by ENS domains, making addresses human-readable.
Shortcuts currently only supports Ethereum Mainnet as the source chain, unless explicitly specified by the Shortcut description. Shortcut addresses are not chain-agnostic, but are different from network to network. Sending ETH (or other tokens) to the wrong network may result in a loss of funds.
How it works: user flow​
A simple use case for a Shortcut could involve a user who wants to streamline the process of bridging ETH to Linea:
- A user sends ETH to a Shortcut address
- The ETH is automatically bridged to Linea via Across
- The ETH is returned as native Linea ETH to the sender on the destination chain (Linea).
More complex Shortcuts can do additional things: bridge and swap, bridge and deposit to a liquidity pool, bridge and stake/restake. The developer's imagination is the only limit.
How it works: technical​
Shortcuts trigger actions using a fallback function in the smart contract called
receive(). This allows users to initiate a transaction without approvals. The
contract engages with Across intent-based listeners and paths that will execute
the action on the destination chain.
The output token(s) from the automation are returned to msg.sender (the
account that called the function; in this case, the person using the Shortcut).
Onthis Snap​
A MetaMask Snap has been built specifically to help you verify that a Shortcut is behaving as intended.
MetaMask Snaps is a system that enables third-party developers to add features and functionality to MetaMask. Read more in the MetaMask Help Center, or visit the Snaps directory to browse what's available.
Before you send funds to the Shortcut, the Snap automatically recognizes that the transaction involves an Onthis Shortcut, and provides a breakdown of:
- The contract address, enabling you to confirm it is correct
- A description of what will happen once you send funds to the Shortcut.
Install the Snap by heading either to the Snaps Directory or the dedicated Onthis page, and then hitting 'Add to MetaMask'.
Fees​
Shortcuts are provided by onthis.xyz and are built on top of Across. Both services charge users a fee on the origin network. This fee covers the bridging costs and automation costs and is shared between the two providers. The fee is calculated as a percentage of the amount transferred, and is on top of the network gas fee paid to execute the origin chain.
Here is an example of the Shortcuts fee model:
| Amount ($) | Swap + bridge fees |
|---|---|
| 100 | 5.4% ($5.40) |
| 500 | 0.5% ($0.50) |
| 1,000 | 0.5% ($5.00) |
| 10,000 | 0.5% ($50.00) |
| 100,000 | 0.5% ($500.00) |
Risks​
Shortcuts do not store value, so the smart contract risk is lower than a traditional dapp. Since they are built on Across, they share its risk profile.
There are several other risks inherent in Shortcuts:
Chain-dependent addressing​
Every Shortcut has a different contract address. Even the same Shortcut deployed on two different networks (Ethereum Mainnet and Arbitrum, for example) will have a different address. Moreover, Shortcuts only work with ETH. Sending tokens (ERC-20, ERC-721, or others) to a Shortcut may result in a loss of funds, as will sending ETH to a Shortcut deployed on a different network.
Linea addresses this risk by clearly identifying the Shortcut's network in its name. If a network is specified, it means that the Shortcut can only accept ETH on that specific network. The naming convention for Shortcut ENS names curated by Linea is as follows:
[network].[usecase/partner].onlinea.eth
In practice, this could look something like:
arbitrum.bridge.onlinea.eth
The omission of the [network] prefix indicates that the Shortcut relates to
Ethereum Mainnet; bridge.onlinea.eth, for example, only works on Ethereum
Mainnet.
Naming system​
The easy UX of sending ETH to an ENS name can present a risk for the user. An attacker can obtain access to the owner key of the ENS name and change the address record, pointing it to their own wallet and collecting the funds sent there.
Linea addresses this risk by controlling the ENS name with a multisig wallet and assigning the manager role to the Linea Security Council (the maximum grade of security). We also have monitors in place that listen for role changes for the ENS name.
Upgradability of contracts​
Shortcuts can be upgraded by the creator. An attacker can upgrade the contract and change its behavior. Linea addresses this risk by requiring trusted creators (like the onthis.xyz team) to hold the owner keys in a secure multisig or asking the creators to hand over the ownership of the contracts to the Linea multisig.
Contract security​
Even though Shortcuts contracts do not store value, security audits are still important. Shortcuts created via the Creator Tool have a deterministic output that is included in the audit scope of the Creator Tool itself. Custom built shortcuts require an independent audit.
Linea addresses this risk by including a third-party audit of the Shortcuts listed under onlinea.eth as part of the curation process.
Further information​
Refer to the official onthis.xyz documentation for more information.
Have you built a tool for Linea? Contribute to the docs to add it here! See our guide to contributing.