Process query and analyze blockchain data including blocks, transactions, and smart contracts.
Use when querying blockchain data and transactions.
Trigger with phrases like "explore blockchain", "query transactions", or "check on-chain data".
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
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.
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.
Append --detailed to the transaction query to decode the function call, identify the interacting protocol, and display input parameters.
Specify --chain polygon, --chain arbitrum, or --chain bsc to query transactions on alternative EVM chains when the hash is not found on Ethereum.
Run python blockchain_explorer.py address <address> to check the native token balance and total transaction count for a wallet.
Add --history --limit 50 to the address query to retrieve the most recent 50 transactions with timestamps, values, and counterparties.
Add --tokens to the address query to list all ERC-20 token holdings with balances, symbols, and USD values via CoinGecko price resolution.
Run python blockchain_explorer.py block latest to inspect the most recent block, or python blockchain_explorer.py block <number> for a specific block.
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.
Export any query result in JSON or CSV format using --format json or --format csv and redirect to a file for downstream processing.
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).
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.
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.