# 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 also possible to query a list of pools from each pool factory.

# 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