What if you could just ask a smart contract questions in plain English?
"What's the total supply?" → calls totalSupply() → "1,000,000 USDC"
"Who is the owner?" → calls owner() → "0x1234...abcd"
"How many holders are there?" → "This contract doesn't have a holder count function, but you could check Transfer events."
I built AbiLens — a chat interface for EVM smart contracts. Paste an address, pick a chain, start asking.
How It Works
The architecture is simple — four steps:
1. Resolve the ABI
When you paste a contract address, AbiLens tries two approaches:
Etherscan API → verified ABI (best case)
↓ (if not verified)
whatsabi → reconstruct ABI from bytecode
whatsabi is the secret weapon here. It reads the deployed bytecode, detects function selectors, follows proxy patterns (EIP-1967), and looks up signatures in the 4byte directory. You get a usable ABI even for unverified contracts.
2. Build Context for the LLM
The system prompt tells the LLM what functions are available:
You are AbiLens. This contract is USDC at 0xA0b8...eB48 on Ethereum.
Available read functions:
name() → string
symbol() → string
decimals() → uint8
totalSupply() → uint256
balanceOf(address account) → uint256
allowance(address owner, address spender) → uint256
The LLM now knows exactly what it can call.
3. LLM Decides What to Call
When you ask "what's the total supply?", the LLM responds with:
{"calls": [{"functionName": "totalSupply", "args": []}]}
AbiLens executes the call using viem:
const result = await client.call({
to: contractAddress,
data: encodeFunctionData({ abi, functionName: "totalSupply", args: [] }),
});
4. LLM Explains the Result
The raw result goes back to the LLM: totalSupply() = 43941622816877670. The LLM knows USDC has 6 decimals (it checked decimals() first) and responds:
"The total supply of USDC is approximately 43.94 billion tokens."
Supported Chains
AbiLens works with any EVM chain. Currently configured:
- Ethereum
- Base
- Arbitrum
- Polygon
- Optimism
- Sepolia (testnet)
Adding a new chain is one object in the config.
Unverified Contracts
This is where AbiLens gets interesting. Most tools require a verified ABI from Etherscan. AbiLens doesn't.
For unverified contracts, whatsabi reconstructs an approximate ABI. The function names might be generic (function_0x1a2b3c), but the types are correct. The LLM adapts:
"This contract has an unverified ABI. I can see a function at selector 0x1a2b3c4d that takes an address and returns a uint256 — this is likely a balance lookup."
The Stack
- viem — EVM interaction (lighter than ethers.js, fully typed)
- whatsabi — ABI reconstruction from bytecode
- Next.js 15 — Web UI with App Router
- Claude / Ollama — LLM provider (works with both)
Try It
git clone https://github.com/pavelEspitia/abilens
cd abilens
cp .env.example .env
# Add your ETHERSCAN_API_KEY to .env
pnpm install && pnpm dev
Paste the USDC address: 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48
Ask: "What is this contract and what can I do with it?"
What's Next
- Write support (with wallet connection)
- Event log querying ("show me the last 10 transfers")
- Multi-contract conversations ("compare the TVL of these two pools")
The code is open source at github.com/pavelEspitia/abilens.
