Imported from jeremylongshore/tons-of-skills-marketplace (plugins/crypto/blockchain-explorer-cli/skills/exploring-blockchain-data/SKILL.md). Install upstream with npx skills add jeremylongshore/tons-of-skills-marketplace --skill exploring-blockchain-data. Copyright stays with the author (MIT).

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

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).

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

exploring-blockchain-data

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