Ethereum Name Service (ENS)

The Ethereum Name Service (ENS) is analogous to the Domain Name Service. It enables users and developers to use human-friendly names in place of error-prone hexadecimal addresses, content hashes, and more.

The ens module is included with It provides an interface to look up domains and addresses, add resolver records, or get and set metadata.

Note v6.6.0 introduced ENS name normalization standard ENSIP-15. This update to ENS name validation and normalization won’t affect ~99% of names but may prevent invalid names from being created and from interacting with the ENS contracts via We feel strongly that this change, though breaking, is in the best interest of our users as it ensures compatibility with the latest ENS standards.


Create an ENS object (named ns below) in one of three ways:

  1. Automatic detection

  2. Specify an instance of a provider

  3. From an existing web3.Web3 object

# automatic detection
from import ns

# or, with a provider
from web3 import IPCProvider
from ens import ENS

provider = IPCProvider(...)
ns = ENS(provider)

# or, with a w3 instance
# Note: This inherits the w3 middlewares from the w3 instance and adds a stalecheck middleware to the middleware onion.
# It also inherits the provider and codec from the w3 instance, as well as the ``strict_bytes_type_checking`` flag value.
from ens import ENS
w3 = Web3(...)
ns = ENS.from_web3(w3)

Asynchronous support is available via the AsyncENS module:

from ens import AsyncENS

ns = AsyncENS(provider)

Note that an ens module instance is also available on the w3 instance. The first time it’s used, will create the ens instance using ENS.from_web3(w3) or AsyncENS.from_web3(w3) as appropriate.

# instantiate w3 instance
from web3 import Web3, IPCProvider
w3 = Web3(IPCProvider(...))

# use the module

The ENS instance has a strict_bytes_type_checking flag that toggles the flag with the same name on the Web3 instance attached to the ENS instance. You may disable the stricter bytes type checking that is loaded by default using this flag. For more examples, see Disabling Strict Checks for Bytes Types

If instantiating a standalone ENS instance using ENS.from_web3(), the ENS instance will inherit the value of the flag on the Web3 instance at time of instantiation.

>>> from web3 import Web3, EthereumTesterProvider
>>> from ens import ENS
>>> w3 = Web3(EthereumTesterProvider())

>>> assert w3.strict_bytes_type_checking  # assert strict by default
>>> w3.is_encodable('bytes2', b'1')

>>> w3.strict_bytes_type_checking = False
>>> w3.is_encodable('bytes2', b'1')  # zero-padded, so encoded to: b'1\x00'

>>> ns = ENS.from_web3(w3)
>>> # assert inherited from w3 at time of instantiation via ENS.from_web3()
>>> assert ns.strict_bytes_type_checking is False
>>> ns.w3.is_encodable('bytes2', b'1')

>>> # assert these are now separate instances
>>> ns.strict_bytes_type_checking = True
>>> ns.w3.is_encodable('bytes2', b'1')

>>> # assert w3 flag value remains
>>> assert w3.strict_bytes_type_checking is False
>>> w3.is_encodable('bytes2', b'1')

However, if accessing the ENS class via the Web3 instance as a module (w3.ens), since all modules use the same Web3 object reference under the hood (the parent w3 object), changing the strict_bytes_type_checking flag value on w3 also changes the flag state for w3.ens.w3 and all modules.

>>> from web3 import Web3, EthereumTesterProvider
>>> w3 = Web3(EthereumTesterProvider())

>>> assert w3.strict_bytes_type_checking  # assert strict by default
>>> w3.is_encodable('bytes2', b'1')

>>> w3.strict_bytes_type_checking = False
>>> w3.is_encodable('bytes2', b'1')  # zero-padded, so encoded to: b'1\x00'

>>> assert w3 == w3.ens.w3  # assert same object
>>> assert not w3.ens.w3.strict_bytes_type_checking
>>> w3.ens.w3.is_encodable('bytes2', b'1')

>>> # sanity check on eth module as well
>>> assert not w3.eth.w3.strict_bytes_type_checking
>>> w3.eth.w3.is_encodable('bytes2', b'1')


Name Info

Get the Address for an ENS Name

from import ns
eth_address = ns.address('ens.eth')
assert eth_address == '0xFe89cc7aBB2C4183683ab71653C4cdc9B02D44b7'

The ENS module has no opinion as to which TLD (Top Level Domain) you can use, but will not infer a TLD if it is not provided with the name.

Multichain Address Resolution

ENSIP-9 introduced multichain address resolution, allowing users to resolve addresses from different chains, specified by the coin type index from SLIP44. The address() method on the ENS class supports multichain address resolution via the coin_type keyword argument.

from import ns
eth_address = ns.address('ens.eth', coin_type=60)  # ETH is coin_type 60
assert eth_address == '0xFe89cc7aBB2C4183683ab71653C4cdc9B02D44b7'

Get the ENS Name for an Address

domain ='0xFe89cc7aBB2C4183683ab71653C4cdc9B02D44b7')

# name() also accepts the bytes version of the address
assert'\xfe\x89\xccz\xbb,A\x83h:\xb7\x16S\xc4\xcd\xc9\xb0-D\xb7') == domain

# confirm that the name resolves back to the address that you looked up:
assert ns.address(domain) == '0xFe89cc7aBB2C4183683ab71653C4cdc9B02D44b7'


For accuracy, and as a recommendation from the ENS documentation on reverse resolution, the ENS module now verifies that the forward resolution matches the address with every call to get the name() for an address. This is the only sure way to know whether the reverse resolution is correct. Anyone can claim any name, only forward resolution implies that the owner of the name gave their stamp of approval.

Get the Owner of a Name

eth_address = ns.owner('exchange.eth')

Set Up Your Name and Address

Text Records

Set Text Metadata for an ENS Record

As the owner of an ENS record, you can add text metadata. A list of supported fields can be found in the ENS documentation. You’ll need to setup the address first, and then the text can be set:

ns.setup_address('ens.eth', '0xFe89cc7aBB2C4183683ab71653C4cdc9B02D44b7')
ns.set_text('ens.eth', 'url', '')

A transaction dictionary can be passed as the last argument if desired:

transaction_dict = {'from': '0x123...'}
ns.set_text('ens.eth', 'url', '', transaction_dict)

If the transaction dictionary is not passed, sensible defaults will be used, and if a transaction dictionary is passed but does not have a from value, the default will be the owner.

Read Text Metadata for an ENS Record

Anyone can read the data from an ENS Record:

url = ns.get_text('ens.eth', 'url')
assert url == ''

Working With Resolvers

Get the Resolver for an ENS Record

You can get the resolver for an ENS name via the resolver() method.

>>> resolver = ns.resolver('ens.eth')
>>> resolver.address

Wildcard Resolution Support

The ENS module supports Wildcard Resolution for resolvers that implement the ExtendedResolver interface as described in ENSIP-10. Resolvers that implement the extended resolver interface should return True when calling the supportsInterface() function with the extended resolver interface id "0x9061b923" and should resolve subdomains to a unique address.