Examples

Here are some common things you might want to do with web3.

Looking up blocks

Blocks can be looked up by either their number or hash using the web3.eth.getBlock API. Block hashes should be in their hexidecimal representation. Block numbers

# get a block by number
>>> web3.eth.getBlock(12345)
{
    'author': '0xad5c1768e5974c231b2148169da064e61910f31a',
    'difficulty': 735512610763,
    'extraData': '0x476574682f76312e302e302f6c696e75782f676f312e342e32',
    'gasLimit': 5000,
    'gasUsed': 0,
    'hash': '0x767c2bfb3bdee3f78676c1285cd757bcd5d8c272cef2eb30d9733800a78c0b6d',
    'logsBloom': '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',
    'miner': '0xad5c1768e5974c231b2148169da064e61910f31a',
    'mixHash': '0x31d9ec7e3855aeba37fd92aa1639845e70b360a60f77f12eff530429ef8cfcba',
    'nonce': '0x549f882c5f356f85',
    'number': 12345,
    'parentHash': '0x4b3c1d7e65a507b62734feca1ee9f27a5379e318bd52ae62de7ba67dbeac66a3',
    'receiptsRoot': '0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421',
    'sealFields': ['0x31d9ec7e3855aeba37fd92aa1639845e70b360a60f77f12eff530429ef8cfcba',
    '0x549f882c5f356f85'],
    'sha3Uncles': '0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347',
    'size': 539,
    'stateRoot': '0xca495e22ed6b88c61714d129dbc8c94f5bf966ac581c09a57c0a72d0e55e7286',
    'timestamp': 1438367030,
    'totalDifficulty': 3862140487204603,
    'transactions': [],
    'transactionsRoot': '0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421',
    'uncles': [],
}
# get a block by it's hash
>>> web3.eth.getBlock('0x767c2bfb3bdee3f78676c1285cd757bcd5d8c272cef2eb30d9733800a78c0b6d')
{...}

Getting the latest block

You can also retrieve the latest block using the string 'latest' in the web3.eth.getBlock API.

>>> web3.eth.getBlock('latest')
{...}

If you want to know the latest block number you can use the web3.eth.blockNumber property.

>>> web3.eth.blockNumber
4194803

Currency conversions

Web3 can help you convert between denominations. The following denominations are supported.

denomination	amount in wei
wei	1
kwei	1000
babbage	1000
femtoether	1000
mwei	1000000
lovelace	1000000
picoether	1000000
gwei	1000000000
shannon	1000000000
nanoether	1000000000
nano	1000000000
szabo	1000000000000
microether	1000000000000
micro	1000000000000
finney	1000000000000000
milliether	1000000000000000
milli	1000000000000000
ether	1000000000000000000
kether	1000000000000000000000
grand	1000000000000000000000
mether	1000000000000000000000000
gether	1000000000000000000000000000
tether	1000000000000000000000000000000

>>> web3.toWei('1', 'ether')
1000000000000000000
>>> web3.fromWei('1000000000000000000', 'ether')
Decimal('1')
>>> from_wei(123456789, 'ether')
Decimal('1.23456789E-10')

Looking up transactions

You can look up transactions using the web3.eth.getTransaction function.

>>> web3.eth.getTransaction('0x5c504ed432cb51138bcf09aa5e8a410dd4a1e204ef84bfed1be16dfba1b22060')
{
    'blockHash': '0x4e3a3754410177e6937ef1f84bba68ea139e8d1a2258c5f85db9f1cd715a1bdd',
    'blockNumber': 46147,
    'condition': None,
    'creates': None,
    'from': '0xa1e4380a3b1f749673e270229993ee55f35663b4',
    'gas': 21000,
    'gasPrice': 50000000000000,
    'hash': '0x5c504ed432cb51138bcf09aa5e8a410dd4a1e204ef84bfed1be16dfba1b22060',
    'input': '0x',
    'networkId': None,
    'nonce': 0,
    'publicKey': '0x376fc429acc35e610f75b14bc96242b13623833569a5bb3d72c17be7e51da0bb58e48e2462a59897cead8ab88e78709f9d24fd6ec24d1456f43aae407a8970e4',
    'r': '0x88ff6cf0fefd94db46111149ae4bfc179e9b94721fffd821d38d16464b3f71d0',
    'raw': '0xf86780862d79883d2000825208945df9b87991262f6ba471f09758cde1c0fc1de734827a69801ca088ff6cf0fefd94db46111149ae4bfc179e9b94721fffd821d38d16464b3f71d0a045e0aff800961cfce805daef7016b9b675c137a6a41a548f7b60a3484c06a33a',
    's': '0x45e0aff800961cfce805daef7016b9b675c137a6a41a548f7b60a3484c06a33a',
    'standardV': '0x1',
    'to': '0x5df9b87991262f6ba471f09758cde1c0fc1de734',
    'transactionIndex': 0,
    'v': '0x1c',
    'value': 31337,
}

If no transaction for the given hash can be found, then this function will instead return None.

Looking up receipts

Transaction receipts can be retrieved using the web3.eth.getTransactionReceipt API.

>>> web3.eth.getTransactionReceipt('0x5c504ed432cb51138bcf09aa5e8a410dd4a1e204ef84bfed1be16dfba1b22060')
{
    'blockHash': '0x4e3a3754410177e6937ef1f84bba68ea139e8d1a2258c5f85db9f1cd715a1bdd',
    'blockNumber': 46147,
    'contractAddress': None,
    'cumulativeGasUsed': 21000,
    'gasUsed': 21000,
    'logs': [],
    'logsBloom': '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',
    'root': '0x96a8e009d2b88b1483e6941e6812e32263b05683fac202abc622a3e31aed1957',
    'transactionHash': '0x5c504ed432cb51138bcf09aa5e8a410dd4a1e204ef84bfed1be16dfba1b22060',
    'transactionIndex': 0,
}

If the transactin has not yet been mined then this method will return None.