Get subdomain from URL using Python

A very basic approach, without any sanity checking could look like:

address = 'http://lol1.domain.com:8888/some/page'

host = address.partition('://')[2]
sub_addr = host.partition('.')[0]

print sub_addr

This of course assumes that when you say ‘subdomain’ you mean the first part of a host name, so in the following case, ‘www’ would be the subdomain:

http://www.google.com/

Is that what you mean?

For extracting the hostname, I’d use urlparse from urllib2:

>>> from urllib2 import urlparse
>>> a = "http://lol1.domain.com:8888/some/page"
>>> urlparse.urlparse(a).hostname
'lol1.domain.com'

As to how to extract the subdomain, you need to cover for the case that there FQDN could be longer. How you do this would depend on your purposes. I might suggest stripping off the two right most components.

E.g.

>>> urlparse.urlparse(a).hostname.rpartition('.')[0].rpartition('.')[0]
'lol1'

What you are looking for is in:
http://docs.python.org/library/urlparse.html

for example:
".".join(urlparse('http://www.my.cwi.nl:80/%7Eguido/Python.html').netloc.split(".")[:-2])

Will do the job for you (will return “www.my”)

Modified version of the fantastic answer here: How to extract top-level domain name (TLD) from URL

You will need the list of effective tlds from here

from __future__ import with_statement
from urlparse import urlparse

# load tlds, ignore comments and empty lines:
with open("effective_tld_names.dat.txt") as tldFile:
    tlds = [line.strip() for line in tldFile if line[0] not in "/n"]

class DomainParts(object):
    def __init__(self, domain_parts, tld):
        self.domain = None
        self.subdomains = None
        self.tld = tld
        if domain_parts:
            self.domain = domain_parts[-1]
            if len(domain_parts) > 1:
                self.subdomains = domain_parts[:-1]

def get_domain_parts(url, tlds):
    urlElements = urlparse(url).hostname.split('.')
    # urlElements = ["abcde","co","uk"]
    for i in range(-len(urlElements),0):
        lastIElements = urlElements[i:]
        #    i=-3: ["abcde","co","uk"]
        #    i=-2: ["co","uk"]
        #    i=-1: ["uk"] etc

        candidate = ".".join(lastIElements) # abcde.co.uk, co.uk, uk
        wildcardCandidate = ".".join(["*"]+lastIElements[1:]) # *.co.uk, *.uk, *
        exceptionCandidate = "!"+candidate

        # match tlds: 
        if (exceptionCandidate in tlds):
            return ".".join(urlElements[i:]) 
        if (candidate in tlds or wildcardCandidate in tlds):
            return DomainParts(urlElements[:i], '.'.join(urlElements[i:]))
            # returns ["abcde"]

    raise ValueError("Domain not in global list of TLDs")

domain_parts = get_domain_parts("http://sub2.sub1.example.co.uk:80",tlds)
print "Domain:", domain_parts.domain
print "Subdomains:", domain_parts.subdomains or "None"
print "TLD:", domain_parts.tld

Gives you:

Domain: example
Subdomains: ['sub2', 'sub1']
TLD: co.uk

Package tldextract makes this task very easy, and then you can use urlparse as suggested if you need any further information:

>>> import tldextract
>>> tldextract.extract("http://lol1.domain.com:8888/some/page"
ExtractResult(subdomain='lol1', domain='domain', suffix='com')
>>> tldextract.extract("http://sub.lol1.domain.com:8888/some/page"
ExtractResult(subdomain='sub.lol1', domain='domain', suffix='com')
>>> urlparse.urlparse("http://sub.lol1.domain.com:8888/some/page")
ParseResult(scheme='http', netloc='sub.lol1.domain.com:8888', path='/some/page', params='', query='', fragment='')

Note that tldextract properly handles sub-domains.

We can use https://github.com/john-kurkowski/tldextract for this problem…

It’s easy.

>>> ext = tldextract.extract('http://forums.bbc.co.uk')
>>> (ext.subdomain, ext.domain, ext.suffix)
('forums', 'bbc', 'co.uk')

tldextract separate the TLD from the registered domain and subdomains of a URL.

Installation

pip install tldextract

For the current question:

import tldextract

address = 'http://lol1.domain.com:8888/some/page'
domain = tldextract.extract(address).domain
print("Extracted domain name : ", domain)

The output:

Extracted domain name :  domain

In addition, there is a number of examples which is extremely related with the usage of tldextract.extract side.

First of All import tldextract, as this splits the URL into its constituents like: subdomain. domain, and suffix.

import tldextract

Then declare a variable (say ext) that stores the results of the query. We also have to provide it with the URL in parenthesis with double quotes. As shown below:

ext = tldextract.extract("http://lol1.domain.com:8888/some/page")

If we simply try to run ext variable, the output will be:

ExtractResult(subdomain='lol1', domain='domain', suffix='com')

Then if you want to use only subdomain or domain or suffix, then use any of the below code, respectively.

ext.subdomain

The result will be:

'lol1'

ext.domain

The result will be:

'domain'

ext.suffix

The result will be:

'com'

Also, if you want to store the results only of subdomain in a variable, then use the code below:

Sub_Domain = ext.subdomain

Then Print Sub_Domain

Sub_Domain

The result will be:

'lol1'

Using python 3 (I’m using 3.9 to be specific), you can do the following:

from urllib.parse import urlparse

address = 'http://lol1.domain.com:8888/some/page'

url = urlparse(address)

url.hostname.split('.')[0]

import re

def extract_domain(domain):
   domain = re.sub('http(s)?://|(:|/)(.*)|','', domain)
   matches = re.findall("([a-z0-9][a-z0-9-]{1,63}.[a-z.]{2,6})$", domain)
   if matches:
       return matches[0]
   else:
       return domain

def extract_subdomains(domain):
   subdomains = domain = re.sub('http(s)?://|(:|/)(.*)|','', domain)
   domain = extract_domain(subdomains)
   subdomains = re.sub('.?'+domain,'', subdomains)
   return subdomains

Example to fetch subdomains:

print(extract_subdomains('http://lol1.domain.com:8888/some/page'))
print(extract_subdomains('kota-tangerang.kpu.go.id'))

Outputs:

lol1
kota-tangerang

Example to fetch domain

print(extract_domain('http://lol1.domain.com:8888/some/page'))
print(extract_domain('kota-tangerang.kpu.go.id'))

Outputs:

domain.com
kpu.go.id

Standardize all domains to start with www. unless they have a subdomain.

from urllib.parse import urlparse
    
def has_subdomain(url):
    if len(url.split('.')) > 2:
        return True
    else:
        return False 

domain = urlparse(url).netloc
        
if not has_subdomain(url):
        domain_name = 'www.' + domain
        url = urlparse(url).scheme + '://' + domain