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47e5dbc Nov 21, 2018
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This simple program may be used to query an Ethereum address to determine if it is a smart contract or simply a regular external account. It may also be used to retrieve the byte-code from an address (if present). Finally, it may be used to compare the byte code found at two addresses to determine if they hold identical code. You may specify multiple addresses on a line.


Usage: isContract [-d|-b|-n|-w|-v|-h] <address> [address...] [block...]
Purpose: Returns 'true' or 'false' if the given address(es) holds byte code (optionally displays the code).


Short Cut Option Description
address_list one or more addresses (0x...) from which to retrieve balances
block_list an optional list of one or more blocks at which to report balances, defaults to 'latest'
-d --data display results as data (addr is_contract)
-b --bytes display the byte code at the address(es)
-n --nodiff return 'true' if (exactly) two Ethereum addresses have identical code
-w --whenDep for smart contracts only, return the first block when the address had code
-v --verbose set verbose level. Either -v, --verbose or -v:n where 'n' is level
-h --help display this help screen


  • addresses must start with '0x' and be forty characters long.
  • block_list may be a space-separated list of values, a start-end range, a special, or any combination.
  • This tool retrieves information from the local node or the ${FALLBACK} node, if configured.
  • If the queried node does not store historical state, the results are undefined.
  • special blocks are detailed under whenBlock --list.

See Also: This command-line tool implements the eth_getCode RPC interface.

Other Options

All QBlocks command-line tools support the following commands (although in some case, they have no meaning):

Command     |     Description
--version   |   display the current version of the tool
--nocolor   |   turn off colored display
--wei       |   specify value in wei (the default)
--ether     |   specify value in ether
--dollars   |   specify value in US dollars
--file:fn   |   specify multiple sets of command line options in a file.

For the --file:fn option, place a series of valid command lines in a file and use the above options. In some cases, this option may significantly improve performance. A semi-colon at the start of a line makes that line a comment.

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