Gasless Transactions
Estimated time to read: 4 minutes
In Web3 apps, blockchain transactions usually require a gas fee. Gasless transactions remove this cost for users, as developers or sponsors cover it.
Using the gasless transaction feature from the Arcana SDKs, developers can simplify user onboarding, reduce entry barriers, and increase app adoption.
Gasless Configuration
Developers can configure gas tanks in the Gasless section of Arcana Developer Dashboard with these steps:
- Add one gas tank per supported blockchain network.
- Deposit or withdraw assets (only the gas tank owner can withdraw).
- Whitelist Web3 app operations by adding verified smart contracts or contract ABIs and specifying functions.
- Optionally, pause or resume gas tanks.
Supported Chains
The Arcana SDKs uses Biconomy Gasless SDK v4 to provide gasless transactions. Developers can set up gas tanks in the Arcana Developer Dashboard to enable gasless operations on supported networks.
Gas Tank Owner
The developer who adds the gas tank for an app becomes its owner. To set up gas tanks, developers must use a MetaMask wallet or any browser-enabled wallet that sets the windows.enabled browser variable. The wallet account used for this setup is called the owner account.
Deposit Funds
After setting up the gas tank, developers can deposit native tokens or ERC-20/ERC-721 tokens for the blockchain network. Third-party wallets or sponsors can also add funds.
Withdraw Funds
Once set up, gas tanks can receive assets from anyone. However, withdrawals are limited to the owner account used for gas tank setup.
Whitelisting App Operations
Setting up the gasless feature involves creating gas tanks, depositing funds, and whitelisting app operations. These operations, executed through smart contracts incur no gas fees for users; the gas tanks cover these costs.
Pause / Enable Gas Tank
After setting up gas tanks, developers can pause or resume them in the Gasless section of Arcana Developer Dashboard. When paused, app users must cover the gas fees.
Gasless Accounts
When gasless transactions are enabled, each authenticated user has two wallet addresses:
- Externally Owned Account (EoA)
- Smart Contract Wallet Account (SCW) - Default
This follows the Ethereum account abstraction standard ERC-4337.
Without a gas tank for the active blockchain network, users only see the EoA account. Once a gas tank is set up, both EoA and SCW accounts appear in the Arcana wallet UI.
Before issuing transactions, developers should check the active account type, as users can switch between EoA and SCW accounts through the wallet UI. Use _arcana_getAccountType() and _arcana_switchAccountType(accountType) methods to manage account types.
Switching EoA and SCW Addresses
By default, when gasless is set up, the SCW address is used in the Arcana wallet UI for transactions. Users can switch to the EoA address, which will incur gas fees from the EoA wallet, regardless of available gas tanks.
If the SCW address is selected but the gas tank is empty, depleted, or paused, gas fees will be charged to the SCW wallet. Users must ensure the SCW wallet has enough funds for gas fees.
Disabling Gasless Capability
Once a gas tank is set up, gasless transactions feature will remain active in Arcana Auth SDK for that blockchain. The EoA and SCW addresses will always be available, even if the gas tank is paused or empty. Users can switch between these addresses in the Arcana wallet UI.
User Keys
Web3 apps with Arcana Auth SDK let authenticated users access their cryptographic keys. Developers can retrieve a user's public key using getPublicKey() from AuthProvider.
For apps configured to use gas tanks, users have EoA and SCW addresses linked to the wallet. getPublicKey() always returns the EoA public key, regardless of the active wallet. There is no public key for the SCW address.
Only authenticated users can export their private key via the Arcana wallet UI. The exported private key is from the EoA account. There is no private key for the SCW address.
How to Issue a Gasless Transaction?
Gasless transactions are available only on select blockchain networks.
Apps can issue gasless transactions via the Arcana wallet or third-party browser-based wallets. As a prerequisite, the apps must be registered and gasless usage must be configured before integrating the app with one or more Arcana SDK.
Prerequisites
- Use the Arcana Developer Dashboard to register the app.
- Configure Gasless Settings
- Set up gas tanks
- Fund gas tanks
- Whitelist app operations by specifying contract ABI and selecting contract functions that will be executed as gasless transactions
Via Arcana wallet
To enable gasless transactions using the Arcana wallet, integrate the app with the Arcana Auth SDK. Onboard users via social login and use the supported Web3 wallet operations for the chosen chain. No additional method is required for gasless transactions. If an operation is whitelisted via gasless settings, users incur no gas fees. Ensure Web3 wallet operations use the SCW Wallet Address, not the EoA Address.
Via Third-party Wallets
To enable gasless transactions using third-party browser-based wallets, integrate the app with the Arcana Gasless (Standalone) SDK. Onboard users via social login and call doTx() method to issue gasless transactions via the third-party wallet. Make sure that the transaction parameter of doTx() invokes a contract function that has already been whitelisted through the gasless configuration settings.
Gasless Transaction for Custom Tokens
To enable a gasless transaction for a custom token on an EVM chain, set the mode parameter to BICONOMY when using doTx(). The following modes are available for gasless transactions through third-party wallets:
| Mode | Use Case |
|---|---|
SCW |
No gasless (default) |
Arcana |
Reserved |
BICONOMY |
Gasless Transaction |
How does Gasless Transaction Work?
Once gasless is set up, not all whitelisted operations are guaranteed to be gasless for the user. It depends on gas availability at the time of the transaction.
Gasless via SCW Address
Only the whitelisted operations issued via smart contract wallets are gasless. Operations from EoA accounts incur gas fees.
When users initiation whitelisted app operations via SCW address, they do not need to pay any gas fees if the gas tanks are funded.
When users initiation whitelisted app operations via SCW address, they may be required to pay gas fees in the following cases.
- Gas tanks are set up and funded but disabled by the developer
- Gas tanks are set up, but no funds are deposited to pay for the gas fees
- Gas tank funds are depleted (used up or if the owner withdraws funds)
