Exploring Blockchain Data

Overview

Query and analyze blockchain data across multiple EVM-compatible networks including Ethereum, Polygon, Arbitrum, Optimism, and BSC. Supports transaction lookups, address balance checks, block inspection, token balance queries, transaction history retrieval, and whale wallet tracking via a unified CLI.

Prerequisites

• Python 3.8+ with requests and web3 libraries installed (pip install requests web3)
• Etherscan API key (free tier provides 5 requests/second; set via ETHERSCAN_API_KEY environment variable)
• Optional: API keys for Polygonscan, Arbiscan, and other chain-specific explorers for higher rate limits
• blockchain_explorer.py CLI script, chain_client.py, and token_resolver.py modules available in the plugin directory
• RPC endpoint access (public endpoints work; dedicated providers like Alchemy, Infura, Chainstack, or QuickNode recommended for reliability)

Instructions

1. Set the Etherscan API key as an environment variable: export ETHERSCAN_API_KEY=<key> to unlock higher rate limits beyond the default 5 requests/second.
2. Run python blockchain_explorer.py tx <hash> to look up a transaction by hash, returning status, block number, from/to addresses, value transferred, and gas details.
3. Append --detailed to the transaction query to decode the function call, identify the interacting protocol, and display input parameters.
4. Specify --chain polygon, --chain arbitrum, or --chain bsc to query transactions on alternative EVM chains when the hash is not found on Ethereum.
5. Run python blockchain_explorer.py address <address> to check the native token balance and total transaction count for a wallet.
6. Add --history --limit 50 to the address query to retrieve the most recent 50 transactions with timestamps, values, and counterparties.
7. Add --tokens to the address query to list all ERC-20 token holdings with balances, symbols, and USD values via CoinGecko price resolution.
8. Run python blockchain_explorer.py block latest to inspect the most recent block, or python blockchain_explorer.py block <number> for a specific block.
9. Run python blockchain_explorer.py token <wallet> <contract> to check the balance of a specific ERC-20 token at a wallet address, with automatic decimal and symbol resolution.
10. Export any query result in JSON or CSV format using --format json or --format csv and redirect to a file for downstream processing.
11. Enable verbose mode with --verbose to display API request URLs, response times, cache hit/miss status, and rate limit counters for debugging.

See ${CLAUDE_SKILL_DIR}/references/implementation.md for the full four-step implementation workflow.

Output

• Transaction detail tables showing hash, chain, status, block number, from/to addresses, value, gas price (Gwei), gas limit, gas used, and gas cost
• Decoded transaction data with function name, protocol identification, and parsed input parameters (when --detailed is used)
• Address summary with native balance, transaction count, and explorer link
• Transaction history tables with timestamp, hash, from/to, value, and direction (in/out)
• Token balance listings with contract address, token name, symbol, raw balance, human-readable balance, and USD value
• Block details with block number, timestamp, transaction count, gas used, and miner/validator
• JSON (output.json) or CSV (transactions.csv) export files for programmatic consumption

Error Handling

Error	Cause	Solution
Transaction not found	Transaction pending in mempool, wrong chain selected, or invalid hash	Wait and retry for pending transactions; try --chain polygon, --chain arbitrum, --chain bsc; verify hash is 66 characters starting with 0x
Explorer API error: Max rate limit reached	Too many requests; no API key or quota exhausted	Wait 1-5 seconds and retry; set ETHERSCAN_API_KEY for higher limits; upgrade to paid tier for production use
RPC error: execution timeout	RPC endpoint overloaded or complex query timed out	Retry with a different RPC endpoint; use a dedicated provider (Alchemy, Infura, QuickNode); simplify the query
Invalid address: 0xinvalid	Address has wrong length, invalid checksum, or non-hex characters	Verify 42 characters with 0x prefix; use the checksummed version from a block explorer; convert to lowercase if checksum fails
Contract source code not verified	Contract source not published on the explorer	Use known function signature databases for decoding; check if the contract is a proxy and look up the implementation address
Token: ??? (Unknown Token)	Token too new, too obscure, or not tracked by CoinGecko	Check the token contract directly on the explorer; look up on a DEX (Uniswap, SushiSwap); manually specify decimals if known
Price: N/A	Token not listed on CoinGecko, API rate limited, or very low liquidity	Check the DEX for on-chain price; use an alternative price feed; calculate from LP reserves
ImportError: No module named 'requests'	Missing Python dependencies	Run pip install requests web3 to install required packages

Examples

Look Up a Transaction Across Chains

# Try Ethereum first, then Polygon if not found
python blockchain_explorer.py tx 0x1234...abcdef --chain ethereum
python blockchain_explorer.py tx 0x1234...abcdef --chain polygon

Returns a formatted table with transaction status, block number, value transferred, gas details, and a link to the block explorer. Adding --detailed decodes the function call (e.g., swapExactTokensForTokens on Uniswap).

Full Wallet Analysis

python blockchain_explorer.py address 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 --history --tokens --limit 50

Produces a wallet summary (ETH balance, total transaction count), the 50 most recent transactions with timestamps and counterparties, and a complete ERC-20 token holdings list with USD values. Useful for whale watching or due diligence on a wallet.

Check USDC Balance and Export to JSON

python blockchain_explorer.py token 0xYourWallet 0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48 --format json > usdc_balance.json

Resolves the USDC contract, fetches the wallet balance with proper decimal handling (6 decimals for USDC), includes the current USD price, and writes the result to usdc_balance.json for integration with dashboards or alerting pipelines.

Resources

• Etherscan API Documentation -- primary explorer API for Ethereum; free tier available with registration
• CoinGecko API -- token price resolution and metadata lookup
• web3.py Documentation -- Python library for direct RPC interaction with EVM chains
• Alchemy / Infura / QuickNode -- dedicated RPC providers for reliable node access
• 4byte.directory -- function signature database for decoding unverified contract interactions