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publicsuffixlist implement

Project description


Public Suffix List parser implementation for Python 2.6+/3.x.

  • Compliant with TEST DATA
  • Support IDN (unicode or punycoded).
  • Support Python2.6+ and Python 3.x
  • Shipped with built-in PSL and the updater script.
  • Written in Pure Python. No library dependencies.

Build Status PyPI version Downloads


publicsuffixlist can be installed via pip or pip3.

$ sudo pip install publicsuffixlist

If you are in a bit old distributions (RHEL/CentOS6.x), you may need to update pip itself before install.

$ sudo pip install -U pip


from publicsuffixlist import PublicSuffixList

psl = PublicSuffixList()
# uses built-in PSL file

psl.publicsuffix("")   # "com"
# longest public suffix part

psl.privatesuffix("")  # ""
# shortest domain assigned for a registrant

psl.privatesuffix("com") # None
# None if no private (non-public) part found

psl.publicsuffix("www.example.unknownnewtld") # "unknownnewtld"
# new TLDs are valid public suffix by default

psl.publicsuffix(u"")   # u"香港"
# accept unicode

psl.publicsuffix("www.example.xn--j6w193g") # "xn--j6w193g"
# accept punycoded IDNs by default

Latest PSL can be passed as a file like line-iterable object.

with open("latest_psl.dat", "rb") as f:
    psl = PublicSuffixList(f)

Works with both Python 2.x and 3.x.

$ python2 test
$ python3 test

Drop-in compatibility code to replace publicsuffix

# from publicsuffix import PublicSuffixList
from publicsuffixlist.compat import PublicSuffixList

psl = PublicSuffixList()
psl.suffix("")   # return ""
psl.suffix("com")               # return "" (as str, not None)

Some convenient methods available.

psl.is_private("")  # True
psl.privateparts("") # ("aaa", "www", "")
psl.subdomain("", depth=1) # ""


publicsuffixlist do NOT provide domain name validation. In DNS protocol, most of 8-bit characters are acceptable label of domain name. ICANN compliant registries do not accept domain names that have _ (underscore) but hostname may have. DMARC records, for example.

Users need to confirm the input is valid based on the users' context.

Partially encoded (Unicode-mixed) Punycode is not supported because of very slow Punycode en/decoding and unpredictable encoding of results. If you are not sure the input is valid Punycode or not, you should do unknowndomain.encode("idna") which is idempotence.

ICANN and private suffixes

The public suffix list contains both suffixes for ICANN domains and private suffixes. Using the flag only_icann the private suffixes can be deactivated:

>>> psl = PublicSuffixList()
>>> psl.publicsuffix("")
>>> psl = PublicSuffixList(only_icann=True)
>>> psl.publicsuffix("")


  • This module is licensed under Mozilla Public License 2.0.
  • Public Suffix List maintained by Mozilla Foundation is licensed under Mozilla Public License 2.0.
  • PSL testcase dataset is public domain (CC0).

Development / Packaging

This module and its packaging workflow are maintained in the author's repository located at A new package, which includes the latest PSL file, is automatically generated and uploaded to PyPI. The last part of the version number represents the release date, for instance,

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