# Fetching Pool List

# Using Balancers API

The Balancer API can be used to retrieve a list of v3 pools and immutable data for calculating swaps. The API is running as a graphql server and is deployed at https://test-api-v3.balancer.fiopen in new window.

The following query can be used to fetch v3 pools with the required immutable data used for swap calculations:

query MyQuery {
    poolGetAggregatorPools(
    where: {chainIn: SEPOLIA, protocolVersionIn: 3, hasHook:false}
    ) {
    id
    type
    poolTokens {
        address
        weight
        isErc4626
        underlyingToken {
        address
        }
    }
    }
}

# Onchain

It is possible to query a list of pools from each pool factory using the following:

/**
* @notice Return a subset of the list of pools deployed by this factory.
* @dev `start` must be a valid index, but if `count` exceeds the total length, it will not revert, but simply
* stop at the end and return fewer results than requested.
*
* @param start The index of the first pool to return
* @param count The maximum number of pools to return
* @return pools The list of pools deployed by this factory, starting at `start` and returning up to `count` pools
*/
function getPoolsInRange(uint256 start, uint256 count) external view returns (address[] memory pools);

/**
* @notice Return the complete list of pools deployed by this factory.
* @return pools The list of pools deployed by this factory
*/
function getPools() external view returns (address[] memory pools);

# Fetching Pool Data

Swap calculations require a combination of data that can be considered as immutable and dynamic. The API can provide both but dynamic data will be subject to a 5minute cache which may not provide the required accuracy. Pools also expose useful view functions that can be used to retrieve this data. These functions follow the format:

getPOOLTYPEPoolDynamicData
e.g.:
- function getStablePoolDynamicData() external view returns (StablePoolDynamicData memory data);

getPOOLTYPEImmutableData
e.g.:
- function getStablePoolImmutableData() external view returns (StablePoolImmutableData memory data);

If a pool is not exposing the helper functions or you prefer to query for specific data the following view functions are available on the Vault and can be used to find onchain pool state:

getPoolTokenRates
getCurrentLiveBalances
getPoolConfig
totalSupply
isPoolPaused
getHooksConfig