Relayers

Opt-in contracts that call the Vault on behalf of users for multi-step operations.

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.

Types of relayers

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]);

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

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.