# tldextract [![PyPI version](https://badge.fury.io/py/tldextract.svg)](https://badge.fury.io/py/tldextract) [![Build Status](https://github.com/john-kurkowski/tldextract/actions/workflows/ci.yml/badge.svg)](https://github.com/john-kurkowski/tldextract/actions/workflows/ci.yml)

`tldextract` accurately separates a URL's subdomain, domain, and public suffix,
using [the Public Suffix List (PSL)](https://publicsuffix.org).

Say you want just the "google" part of https://www.google.com. *Everybody gets
this wrong.* Splitting on the "." and taking the 2nd-to-last element only works
for simple domains, e.g. .com. Consider
[http://forums.bbc.co.uk](http://forums.bbc.co.uk): the naive splitting method
will give you "co" as the domain, instead of "bbc". Rather than juggle TLDs,
gTLDs, or ccTLDs  yourself, `tldextract` extracts the currently living public
suffixes according to [the Public Suffix List](https://publicsuffix.org).

> A "public suffix" is one under which Internet users can directly register
> names.

A public suffix is also sometimes called an effective TLD (eTLD).

## Usage

```python
>>> import tldextract

>>> tldextract.extract('http://forums.news.cnn.com/')
ExtractResult(subdomain='forums.news', domain='cnn', suffix='com', is_private=False)

>>> tldextract.extract('http://forums.bbc.co.uk/') # United Kingdom
ExtractResult(subdomain='forums', domain='bbc', suffix='co.uk', is_private=False)

>>> tldextract.extract('http://www.worldbank.org.kg/') # Kyrgyzstan
ExtractResult(subdomain='www', domain='worldbank', suffix='org.kg', is_private=False)
```

Note subdomain and suffix are _optional_. Not all URL-like inputs have a
subdomain or a valid suffix.

```python
>>> tldextract.extract('google.com')
ExtractResult(subdomain='', domain='google', suffix='com', is_private=False)

>>> tldextract.extract('google.notavalidsuffix')
ExtractResult(subdomain='google', domain='notavalidsuffix', suffix='', is_private=False)

>>> tldextract.extract('http://127.0.0.1:8080/deployed/')
ExtractResult(subdomain='', domain='127.0.0.1', suffix='', is_private=False)
```

To rejoin the original hostname, if it was indeed a valid, registered hostname:

```python
>>> ext = tldextract.extract('http://forums.bbc.co.uk')
>>> ext.top_domain_under_public_suffix
'bbc.co.uk'
>>> ext.fqdn
'forums.bbc.co.uk'
```

In addition to the Python interface, there is a command-line interface. Split
the URL components by space:

```zsh
$ tldextract 'http://forums.bbc.co.uk'
forums bbc co.uk
```

By default, this package supports the public ICANN TLDs and their exceptions.
You can optionally support the Public Suffix List's [private
domains](#public-vs-private-domains) as well.

This package started by implementing the chosen answer from [this StackOverflow question on
getting the "domain name" from a URL](http://stackoverflow.com/questions/569137/how-to-get-domain-name-from-url/569219#569219).
However, the proposed regex solution doesn't address many country codes like
com.au, or the exceptions to country codes like the registered domain
parliament.uk. The Public Suffix List does, and so does this package.

## Install

Latest release on PyPI:

```zsh
pip install tldextract
```

Or the latest dev version:

```zsh
pip install -e 'git://github.com/john-kurkowski/tldextract.git#egg=tldextract'
```

## Note about caching

Beware when first calling `tldextract`, it updates its TLD list with a live HTTP
request. This updated TLD set is usually cached indefinitely in `$HOME/.cache/python-tldextract`.
To control the cache's location, set the `TLDEXTRACT_CACHE` environment variable or set the
`cache_dir` path when constructing a `TLDExtract`.

(Arguably runtime bootstrapping like that shouldn't be the default behavior,
like for production systems. But I want you to have the latest TLDs, especially
when I haven't kept this code up to date.)


```python
# extract callable that falls back to the included TLD snapshot, no live HTTP fetching
no_fetch_extract = tldextract.TLDExtract(suffix_list_urls=())
no_fetch_extract('http://www.google.com')

# extract callable that reads/writes the updated TLD set to a different path
custom_cache_extract = tldextract.TLDExtract(cache_dir='/path/to/your/cache/')
custom_cache_extract('http://www.google.com')

# extract callable that doesn't use caching
no_cache_extract = tldextract.TLDExtract(cache_dir=None)
no_cache_extract('http://www.google.com')
```

If you want to stay fresh with the TLD definitions--though they don't change
often--delete the cache file occasionally, or run

```zsh
tldextract --update
```

or:

```zsh
env TLDEXTRACT_CACHE="~/tldextract.cache" tldextract --update
```

It is also recommended to delete the file after upgrading this lib.

## Advanced usage

### Public vs. private domains

The PSL [maintains a concept of "private"
domains](https://publicsuffix.org/list/).

> PRIVATE domains are amendments submitted by the domain holder, as an
> expression of how they operate their domain security policy. … While some
> applications, such as browsers when considering cookie-setting, treat all
> entries the same, other applications may wish to treat ICANN domains and
> PRIVATE domains differently.

By default, `tldextract` treats public and private domains the same.

```python
>>> extract = tldextract.TLDExtract()
>>> extract('waiterrant.blogspot.com')
ExtractResult(subdomain='waiterrant', domain='blogspot', suffix='com', is_private=False)
```

The following overrides this.

```python
>>> extract = tldextract.TLDExtract()
>>> extract('waiterrant.blogspot.com', include_psl_private_domains=True)
ExtractResult(subdomain='', domain='waiterrant', suffix='blogspot.com', is_private=True)
```

To change the default for all extract calls:

```python
>>> extract = tldextract.TLDExtract(include_psl_private_domains=True)
>>> extract('waiterrant.blogspot.com')
ExtractResult(subdomain='', domain='waiterrant', suffix='blogspot.com', is_private=True)
```

The thinking behind the default is, it's the more common case when people
mentally parse a domain name. It doesn't assume familiarity with the PSL nor
that the PSL makes a public/private distinction. Note this default may run
counter to the default parsing behavior of other, PSL-based libraries.

### Specifying your own URL or file for Public Suffix List data

You can specify your own input data in place of the default Mozilla Public Suffix List:

```python
extract = tldextract.TLDExtract(
    suffix_list_urls=["http://foo.bar.baz"],
    # Recommended: Specify your own cache file, to minimize ambiguities about where
    # tldextract is getting its data, or cached data, from.
    cache_dir='/path/to/your/cache/',
    fallback_to_snapshot=False)
```

If the cached version of public suffix definitions doesn't exist, such as on
the first run, the above snippet will request the URLs you specified in order,
and use the first successful response.

If you want to use input data from your local filesystem, use the `file://`
protocol with an absolute path:

```python
extract = tldextract.TLDExtract(
    suffix_list_urls=["file://" + "/absolute/path/to/your/local/suffix/list/file"],
    cache_dir='/path/to/your/cache/',
    fallback_to_snapshot=False)
```

This also works via command line update:

```zsh
tldextract --update --suffix_list_url "http://foo.bar.baz"
```

Using your own URLs could be useful in production when you don't want the delay
with updating the suffix list on first use, or if you are behind a complex
firewall.

You can also specify additional suffixes in the `extra_suffixes` param. These
will be merged into whatever public suffix definitions are already in use by
`tldextract`.

```python
extract = tldextract.TLDExtract(
    extra_suffixes=["foo", "bar", "baz"])
```

## FAQ

### Can you add suffix \_\_\_\_? Can you make an exception for domain \_\_\_\_?

This project doesn't contain an actual list of public suffixes. That comes from
[the Public Suffix List (PSL)](https://publicsuffix.org/). Submit amendments there.

In the meantime, you can tell tldextract about your exception by either
forking the PSL and using your fork in the `suffix_list_urls` param, or adding
your suffix piecemeal with the `extra_suffixes` param.

### I see my suffix in [the Public Suffix List (PSL)](https://publicsuffix.org/), but this library doesn't extract it.

Check if your suffix is in the private section of the list. See [this
documentation](#public-vs-private-domains).

### If I pass an invalid URL, I still get a result, no error. What gives?

To keep `tldextract` light in LoC & overhead, and because there are plenty of
URL validators out there, this library is very lenient with input. If valid
URLs are important to you, validate them before calling `tldextract`.

To avoid parsing a string twice, you can pass `tldextract` the output of
[`urllib.parse`](https://docs.python.org/3/library/urllib.parse.html) methods.
For example:

```py
extractor = TLDExtract()
split_url = urllib.parse.urlsplit("https://foo.bar.com:8080")
split_suffix = extractor.extract_urllib(split_url)
url_to_crawl = f"{split_url.scheme}://{split_suffix.top_domain_under_public_suffix}:{split_url.port}"
```

`tldextract`'s lenient string parsing stance lowers the learning curve of using
the library, at the cost of desensitizing users to the nuances of URLs. This
could be overhauled. For example, users could opt into validation, either
receiving exceptions or error metadata on results.

## Contribute

### Setting up

1. `git clone` this repository.
2. Change into the new directory.
3. `pip install --upgrade --editable '.[testing]'`

### Running the test suite

Run all tests against all supported Python versions:

```zsh
tox --parallel
```

Run all tests against a specific Python environment configuration:

```zsh
tox -l
tox -e py311
```

### Code Style

Automatically format all code:

```zsh
ruff format .
```
