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Relayers are opt-in, audited contracts that can make calls to the Vault on your behalf. They can use the sender’s ERC20 vault allowance, internal balance, or BPTs after being approved.

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Types of relayers

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BalancerRelayer

The BalancerRelayer allows you to execute multiple vault actions in a single transaction by chaining them together. This improves UX by reducing the number of transactions needed for complex operations. Example of chaining multiple actions: 
// Approve relayer
const approval = buildApproval(signature);

// Chain exit pool and swap
const exitPoolCallData = buildExitPool(poolId, bptAmount);
const swapCallData = buildSwap(params);

// Execute all actions in one transaction
const tx = await relayer.multicall([approval, exitPoolCallData, swapCallData]);

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PoolCreationHelper

The PoolCreationHelper is a specialized relayer that simplifies pool creation and initial liquidity provision. See the PoolCreationHelper documentation for details. Key features:
  • Creates and joins pools in a single transaction
  • Supports joining WBERA pools with either WBERA or BERA
  • Handles both weighted and stable pool creation

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Approving a relayer

Before a relayer can act on your behalf, you must approve it using the Vault’s setRelayerApproval function: 
function setRelayerApproval(
    address sender,
    address relayer,
    bool approved
) external;
For example, to approve the PoolCreationHelper: 
const vault = new ethers.Contract(VAULT_ADDRESS, vaultAbi, wallet);
await vault.setRelayerApproval(
  wallet.address, // sender
  RELAYER_ADDRESS, // relayer
  true // approved
);
Only approve relayers that have been audited and are part of the official BEX deployment.