How to Programmatically Retrieve Uniswap V3 ETH/USDC Pool Balances with Python

Why Access the Blockchain Directly?

In DeFi, data equals money. Querying pool information directly from the chain provides reliable, decentralized, 24/7 automation and avoids latency, outages, or errors that centralized APIs may introduce.

Core Idea: Talk to the Smart Contract

Liquidity pools are smart contracts that hold user‑deposited tokens. To obtain a pool’s asset status, query the contract’s token balances (ETH/WETH and USDC) via the ERC‑20 balanceOf function. For Uniswap V3 this is the most straightforward and reliable method.

Step‑by‑Step Process

Connect to an Ethereum node Use a provider such as Infura, Alchemy, or a self‑hosted node.

Locate the target contracts Identify the Uniswap V3 ETH/USDC pool address and the token contract addresses for WETH and USDC.

Use a minimal ERC‑20 ABI Include only the balanceOf , decimals , and symbol functions.

Execute the query and parse results Call balanceOf(pool_address).call() for each token, then adjust for token decimals.

Visual overview of the workflow:

Hands‑On Demo: Query with Python and Web3.py

Install the library: pip install web3 You also need an Ethereum node URL (Infura, Alchemy, or a local node).

Key Addresses on Mainnet

Uniswap V3 Pool (ETH/USDC 0.3%) 0x88e6a0c2ddd26feeb64f039a2c41296fcb3f5640 WETH Token 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 USDC Token

0xA0b86991c6218b36c1d19d4a2e9eb0ce3606eb48

Core Python Code

from web3 import Web3

# 1. Preparation
infura_url = "https://mainnet.infura.io/v3/72a0c21cf2854a9d810d8986b88b9e8d"
web3 = Web3(Web3.HTTPProvider(infura_url))
if not web3.is_connected():
    raise ConnectionError("Unable to connect to Ethereum node")
print("Connected to Ethereum node!")

# 2. Define addresses and a minimal ERC‑20 ABI
pool_address = web3.to_checksum_address("0x88e6a0c2ddd26feeb64f039a2c41296fcb3f5640")
weth_address = web3.to_checksum_address("0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2")
usdc_address = web3.to_checksum_address("0xA0b86991c6218b36c1d19d4a2e9eb0ce3606eb48")
erc20_abi = [
    {"constant": True, "inputs": [{"name": "_owner", "type": "address"}], "name": "balanceOf", "outputs": [{"name": "balance", "type": "uint256"}], "type": "function"},
    {"constant": True, "inputs": [], "name": "decimals", "outputs": [{"name": "", "type": "uint8"}], "type": "function"},
    {"constant": True, "inputs": [], "name": "symbol", "outputs": [{"name": "", "type": "string"}], "type": "function"}
]

# 3. Create contract instances
weth_contract = web3.eth.contract(address=weth_address, abi=erc20_abi)
usdc_contract = web3.eth.contract(address=usdc_address, abi=erc20_abi)

# 4. Query raw balances
weth_balance_raw = weth_contract.functions.balanceOf(pool_address).call()
usdc_balance_raw = usdc_contract.functions.balanceOf(pool_address).call()

# 5. Adjust for decimals
weth_decimals = weth_contract.functions.decimals().call()
usdc_decimals = usdc_contract.functions.decimals().call()
weth_balance = weth_balance_raw / (10 ** weth_decimals)
usdc_balance = usdc_balance_raw / (10 ** usdc_decimals)

# 6. Get token symbols
weth_symbol = weth_contract.functions.symbol().call()
usdc_symbol = usdc_contract.functions.symbol().call()

# 7. Print results
print(f"  {weth_symbol} balance: {weth_balance:.4f}")
print(f"  {usdc_symbol} balance: {usdc_balance:.2f}")

Code Walkthrough

web3.to_checksum_address ensures addresses are correctly formatted, avoiding case‑sensitivity issues.

erc20_abi includes only the balanceOf, decimals, and symbol functions, which are sufficient for balance queries.

.call() performs a read‑only operation that does not consume gas.

Handling Decimals – On‑chain balances are integers; dividing by 10**decimals converts them to human‑readable values (WETH = 18 decimals, USDC = 6 decimals).

Conclusion & Practical Recommendations

The method equips you with the core skill of automatically monitoring DEX pool assets directly from the blockchain, eliminating reliance on centralized services and providing a foundation for more advanced on‑chain tools.

Practical tips:

Extend to other pools – Locate the desired pool and token addresses (via Etherscan or DEX documentation) and reuse the same script.

Query historical data – Pass a block_identifier to .call(), e.g., balanceOf(pool_address).call(block_identifier=18000000), to retrieve balances at a specific block.

Select reliable node providers – For production, use paid, high‑availability services with fallback nodes.

Stay updated – DeFi evolves rapidly; monitor upcoming upgrades such as Uniswap V4.