jiayaoqijia Crypto Wallet
Query on-chain wallet data: balances, tokens, transactions, approvals, and ENS resolution.
Common ERC-20 Function Selectors
| Function | Selector | Params |
|---|---|---|
balanceOf(address) |
0x70a08231 |
address (32 bytes, left-padded) |
allowance(address,address) |
0xdd62ed3e |
owner + spender (each 32 bytes) |
decimals() |
0x313ce567 |
none |
symbol() |
0x95d89b41 |
none |
name() |
0x06fdde03 |
none |
totalSupply() |
0x18160ddd |
none |
APIs
ETH Balance via Public RPC
Native ETH balance (eth_getBalance):
exec command="curl -s -X POST https://eth.llamarpc.com -H 'Content-Type: application/json' -d '{\"jsonrpc\":\"2.0\",\"method\":\"eth_getBalance\",\"params\":[\"0xADDRESS\",\"latest\"],\"id\":1}'"
ERC-20 token balance (eth_call with balanceOf):
exec command="curl -s -X POST https://eth.llamarpc.com -H 'Content-Type: application/json' -d '{\"jsonrpc\":\"2.0\",\"method\":\"eth_call\",\"params\":[{\"to\":\"0xTOKEN_CONTRACT\",\"data\":\"0x70a08231000000000000000000000000WALLET_NO_0x\"},\"latest\"],\"id\":1}'"
Result is hex. Convert:
parseInt(result, 16) / 10^decimals
Multi-chain Public RPCs
| Chain | RPC URL |
|---|---|
| Ethereum | https://eth.llamarpc.com |
| Arbitrum | https://arb1.arbitrum.io/rpc |
| Optimism | https://mainnet.optimism.io |
| Base | https://mainnet.base.org |
| Polygon | https://polygon-rpc.com |
| BSC | https://bsc-dataseed.binance.org |
| Avalanche | https://api.avax.network/ext/bc/C/rpc |
Etherscan / Block Explorers (Free tier, API key optional)
Base URLs:
- Ethereum:
https://api.etherscan.io/api - Arbitrum:
https://api.arbiscan.io/api - Base:
https://api.basescan.org/api - Optimism:
https://api-optimistic.etherscan.io/api - Polygon:
https://api.polygonscan.com/api - BSC:
https://api.bscscan.com/api
Token balances for address (requires free API key):
web_fetch url="https://api.etherscan.io/api?module=account&action=tokentx&address=0xADDRESS&page=1&offset=50&sort=desc&apikey=YOUR_KEY"
Normal transactions:
web_fetch url="https://api.etherscan.io/api?module=account&action=txlist&address=0xADDRESS&startblock=0&endblock=99999999&page=1&offset=20&sort=desc&apikey=YOUR_KEY"
ETH balance (no key needed, rate limited):
web_fetch url="https://api.etherscan.io/api?module=account&action=balance&address=0xADDRESS&tag=latest"
ENS Resolution
Forward (name to address) via RPC:
exec command="curl -s -X POST https://eth.llamarpc.com -H 'Content-Type: application/json' -d '{\"jsonrpc\":\"2.0\",\"method\":\"eth_call\",\"params\":[{\"to\":\"0x4976fb03C32e5B8cfe2b6cCB31c09Ba78EBaBa41\",\"data\":\"0x3b3b57de{NAMEHASH}\"},\"latest\"],\"id\":1}'"
Simpler: use ENS public API:
web_fetch url="https://ensdata.net/ADDRESS_OR_NAME"
Token Approvals
Check allowance (how much a spender can use):
exec command="curl -s -X POST https://eth.llamarpc.com -H 'Content-Type: application/json' -d '{\"jsonrpc\":\"2.0\",\"method\":\"eth_call\",\"params\":[{\"to\":\"0xTOKEN\",\"data\":\"0xdd62ed3e000000000000000000000000OWNER_NO_0x000000000000000000000000SPENDER_NO_0x\"},\"latest\"],\"id\":1}'"
Unlimited approval =
0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
External Tools (Optional)
- EVM MCP Server:
npx @mcpdotdirect/evm-mcp-server— read balances, tokens, NFTs across 60+ EVM chains - Base MCP:
github.com/base/base-mcp— Coinbase-official Base chain tools
Usage Tips
- Always pad addresses to 32 bytes (64 hex chars) in eth_call data fields
- Strip
0xprefix from address when embedding in calldata, then left-pad with zeros - Results from eth_call are hex-encoded; parse with
parseInt(hex, 16) - For ERC-20 balances, divide by
10^decimals(USDC=6, most tokens=18) - For multi-token portfolios, use Etherscan tokentx endpoint rather than individual RPC calls
- Verify chain before querying — same address can exist on multiple chains with different balances