Public Suffix List and IANA Root Zone Database based Domain parsing implemented in PHP.

Fund package maintenance!

Installs: 9 353 015

Dependents: 63

Suggesters: 4

Security: 0

Stars: 1 140

Watchers: 29

Forks: 126

Open Issues: 0

6.3.0 2023-02-25 16:31 UTC


PHP Domain Parser is a resource based domain parser implemented in PHP.

Build Status Total Downloads Latest Stable Version Software License


While there are plenty of excellent URL parsers and builders available, there are very few projects that can accurately parse a domain into its component subdomain, registrable domain, second level domain and public suffix parts.

Consider the domain In this domain, the public suffix portion is, the registrable domain is, the subdomain is www and the second level domain is pref.
You can't regex that.

PHP Domain Parser is compliant around:

  • accurate Public Suffix List based parsing.
  • accurate IANA Top Level Domain List parsing.



composer require jeremykendall/php-domain-parser:^6.0

System Requirements

You need:



If you are upgrading from version 5 please check the upgrading guide for known issues.

Resolving Domains

This library can resolve a domain against:

In both cases this is done using the resolve method implemented on the resource instance. The method returns a Pdp\ResolvedDomain object which represents the result of that process.

For the Public Suffix List you need to use the Pdp\Rules class as shown below:

use Pdp\Rules;
use Pdp\Domain;

$publicSuffixList = Rules::fromPath('/path/to/cache/public-suffix-list.dat');
$domain = Domain::fromIDNA2008('www.PreF.OkiNawA.jP');

$result = $publicSuffixList->resolve($domain);
echo $result->domain()->toString();            //display '';
echo $result->subDomain()->toString();         //display 'www';
echo $result->secondLevelDomain()->toString(); //display 'pref';
echo $result->registrableDomain()->toString(); //display '';
echo $result->suffix()->toString();            //display '';
$result->suffix()->isICANN();                  //return true;

For the IANA Top Level Domain List, the Pdp\TopLevelDomains class is use instead:


use Pdp\Domain;
use Pdp\TopLevelDomains;

$topLevelDomains = TopLevelDomains::fromPath('/path/to/cache/tlds-alpha-by-domain.txt');
$domain = Domain::fromIDNA2008('www.PreF.OkiNawA.jP');

$result = $topLevelDomains->resolve($domain);
echo $result->domain()->toString();            //display '';
echo $result->suffix()->toString();            //display 'jp';
echo $result->secondLevelDomain()->toString(); //display 'okinawa';
echo $result->registrableDomain()->toString(); //display '';
echo $result->subDomain()->toString();         //display 'www.pref';
echo $result->suffix()->isIANA();              //return true

In case of an error an exception which extends Pdp\CannotProcessHost is thrown.

The resolve method will always return a ResolvedDomain even if the domain syntax is invalid or if there is no match found in the resource data. To work around this limitation, the library exposes more strict methods, namely:

  • Rules::getCookieDomain
  • Rules::getICANNDomain
  • Rules::getPrivateDomain

for the Public Suffix List and the following method for the Top Level Domain List:

  • TopLevelDomains::getIANADomain

These methods resolve the domain against their respective data source using the same rules as the resolve method but will instead throw an exception if no valid effective TLD is found or if the submitted domain is invalid.


All these methods expect as their sole argument a Pdp\Host implementing object, but other types (ie: string, null and stringable objects) are supported with predefined conditions as explained in the remaining document.


use Pdp\Domain;
use Pdp\Rules;
use Pdp\TopLevelDomains;

$publicSuffixList = Rules::fromPath('/path/to/cache/public-suffix-list.dat');
$domain = Domain::fromIDNA2008('qfdsf.unknownTLD');

// will throw because `.unknownTLD` is not part of the ICANN section

$result = $publicSuffixList->getCookieDomain($domain);
$result->suffix()->value();   // returns 'unknownTLD'
$result->suffix()->isKnown(); // returns false
// will not throw because the domain syntax is correct.

// will not throw because the domain syntax is invalid (ie: does not support public suffix)

$result = $publicSuffixList->resolve(Domain::fromIDNA2008('com'));
$result->suffix()->value();   // returns null
$result->suffix()->isKnown(); // returns false
// will not throw but its public suffix value equal to NULL

$topLevelDomains = TopLevelDomains::fromPath('/path/to/cache/public-suffix-list.dat');
// will not throw because the domain syntax is invalid (ie: does not support public suffix)

To instantiate each domain resolver you can use the following named constructor:

  • fromString: instantiate the resolver from a inline string representing the data source;
  • fromPath: instantiate the resolver from a local path or online URL by relying on fopen;

If the instantiation does not work an exception will be thrown.


You SHOULD never resolve domain name this way in production, without, at least, a caching mechanism to reduce external resource downloads. Using the Public Suffix List to determine what is a valid domain name and what isn't is dangerous, and MAY lead to errors because of new gTLDs being registered on a regular basis. If you are looking to know the validity of a Top Level Domain, you MUST use the IANA Top Level Domain List as the proper source for this information or alternatively the DNS. If you MUST use this library for any of the above purposes, you SHOULD consider integrating an updating mechanism into your software. For more information go to the Managing external data source section**

Resolved domain information.

Whichever methods chosen to resolve the domain on success, the package will return a Pdp\ResolvedDomain instance.

The Pdp\ResolvedDomain decorates the Pdp\Domain class resolved but also gives access as separate methods to the domain different components.

use Pdp\Domain;
use Pdp\TopLevelDomains;

$domain = Domain::fromIDNA2008('www.PreF.OkiNawA.jP');
/** @var TopLevelDomains $topLevelDomains */
$result = $topLevelDomains->resolve($domain);
echo $result->domain()->toString();            //display '';
echo $result->suffix()->toString();            //display 'jp';
echo $result->secondLevelDomain()->toString(); //display 'okinawa';
echo $result->registrableDomain()->toString(); //display '';
echo $result->subDomain()->toString();         //display 'www.pref';
echo $result->suffix()->isIANA();              //return true

You can modify the returned Pdp\ResolvedDomain instance using the following methods:


use Pdp\Domain;
use Pdp\Rules;

/** @var Rules $publicSuffixList */
$result = $publicSuffixList->resolve(Domain::fromIDNA2008(''));
$altResult = $result

echo $result->domain()->toString(); //display '';
$result->suffix()->isKnown();       //return true;

echo $altResult->domain()->toString(); //display '';
$altResult->suffix()->isKnown();       //return false;


Always favor submitting a Pdp\Suffix object rather that any other supported type to avoid unexpected results. By default, if the input is not a Pdp\Suffix instance, the resulting public suffix will be labelled as being unknown. For more information go to the Public Suffix section

Domain Suffix

The domain effective TLD is represented using the Pdp\Suffix. Depending on the data source the object exposes different information regarding its origin.

use Pdp\Domain;
use Pdp\Rules;

/** @var Rules $publicSuffixList */
$suffix = $publicSuffixList->resolve(Domain::fromIDNA2008(''))->suffix();

echo $suffix->domain()->toString(); //display '';
$suffix->isICANN();                 //will return false
$suffix->isPrivate();               //will return true
$suffix->isPublicSuffix();          //will return true
$suffix->isIANA();                  //will return false
$suffix->isKnown();                 //will return true

The public suffix state depends on its origin:

  • isKnown returns true if the value is present in the data resource.
  • isIANA returns true if the value is present in the IANA Top Level Domain List.
  • isPublicSuffix returns true if the value is present in the Public Suffix List.
  • isICANN returns true if the value is present in the Public Suffix List ICANN section.
  • isPrivate returns true if the value is present in the Public Suffix List private section.

The same information is used when Pdp\Suffix object is instantiate via its named constructors:

use Pdp\Suffix;

$iana = Suffix::fromIANA('');
$icann = Suffix::fromICANN('');
$private = Suffix::fromPrivate('');
$unknown = Suffix::fromUnknown('');

Using a Suffix object instead of a string or null with ResolvedDomain::withSuffix will ensure that the returned value will always contain the correct information regarding the public suffix resolution.

Using a Domain object instead of a string or null with the named constructor ensure a better instantiation of the Public Suffix object for more information go to the ASCII and Unicode format section

Accessing and processing Domain labels

If you are interested into manipulating the domain labels without taking into account the Effective TLD, the library provides a Domain object tailored for manipulating domain labels. You can access the object using the following methods:

  • the ResolvedDomain::domain method
  • the ResolvedDomain::subDomain method
  • the ResolvedDomain::registrableDomain method
  • the ResolvedDomain::secondLevelDomain method
  • the Suffix::domain method

Domain objects usage are explain in the next section.

use Pdp\Domain;
use Pdp\Rules;

/** @var Rules $publicSuffixList */
$result = $publicSuffixList->resolve(Domain::from2008(''));
$domain = $result->domain();
echo $domain->toString(); // display ''
count($domain);           // returns 4
$domain->labels();        // returns ['uk', 'co', 'bbc', 'www'];
$domain->label(-1);       // returns 'www'
$domain->label(0);        // returns 'uk'
foreach ($domain as $label) {
   echo $label, PHP_EOL;
// display 
// uk
// co
// bbc
// www

$publicSuffixDomain = $result->suffix()->domain();
$publicSuffixDomain->labels(); // returns ['uk', 'co']

You can also add or remove labels according to their key index using the following methods:

use Pdp\Domain;
use Pdp\Rules;

/** @var Rules $publicSuffixList */
$domain = $publicSuffixList->resolve(Domain::from2008('www.ExAmpLE.cOM'))->domain();

$newDomain = $domain
    ->withLabel(1, 'com')  //replace 'example' by 'com'
    ->withoutLabel(0, -1)  //remove the first and last labels

echo $domain->toString();           //display ''
echo $newDomain->toString();        //display ''
$newDomain->clear()->labels();      //return []
echo $domain->slice(2)->toString(); //display 'www'


Because of its definition, a domain name can be null or a string.

To distinguish this possibility the object exposes two (2) formatting methods Domain::value which can be null or a string and Domain::toString which will always cast the domain value to a string.

use Pdp\Domain;

$nullDomain = Domain::fromIDNA2008(null);
$nullDomain->value();    // returns null;
$nullDomain->toString(); // returns '';

$emptyDomain = Domain::fromIDNA2008('');
$emptyDomain->value();    // returns '';
$emptyDomain->toString(); // returns '';

ASCII and Unicode formats.

Domain names originally only supported ASCII characters. Nowadays, they can also be presented under a UNICODE representation. The conversion between both formats is done using the compliant implementation of UTS#46, otherwise known as Unicode IDNA Compatibility Processing. Domain objects expose a toAscii and a toUnicode methods which returns a new instance in the converted format.

use Pdp\Rules;

/** @var Rules $publicSuffixList */
$unicodeDomain = $publicSuffixList->resolve('bébé.be')->domain();
echo $unicodeDomain->toString(); // returns 'bébé.be'

$asciiDomain = $publicSuffixList->resolve('')->domain();
echo $asciiDomain->toString();  // returns ''

$asciiDomain->toUnicode()->toString() === $unicodeDomain->toString(); //returns true
$unicodeDomain->toAscii()->toString() === $asciiDomain->toString();   //returns true

By default, the library uses IDNA2008 algorithm to convert domain name between both formats. It is still possible to use the legacy conversion algorithm known as IDNA2003.

Since direct conversion between both algorithms is not possible you need to explicitly specific on construction which algorithm you will use when creating a new domain instance via the Pdp\Domain object. This is done via two (2) named constructors:

  • Pdp\Domain::fromIDNA2008
  • Pdp\Domain::fromIDNA2003

At any given moment the Pdp\Domain instance can tell you whether it is in ASCII mode or not.


Once instantiated there's no way to tell which algorithm is used to convert the object from ascii to unicode and vice-versa

use Pdp\Domain;

$domain = Domain::fromIDNA2008('faß.de');
echo $domain->value(); // display 'faß.de'
$domain->isAscii();    // return false

$asciiDomain = $domain->toAscii(); 
echo $asciiDomain->value(); // display ''
$asciiDomain->isAscii();    // returns true

$domain = Domain::fromIDNA2003('faß.de');
echo $domain->value(); // display ''
$domain->isAscii();    // returns true

$asciiDomain = $domain->toAscii();
echo $asciiDomain->value(); // display ''
$asciiDomain->isAscii();    // returns true


Always favor submitting a Pdp\Domain object for resolution rather that a string or an object that can be cast to a string to avoid unexpected format conversion errors/results. By default, and with lack of information conversion is done using IDNA 2008 rules.

Managing the package external resources

Depending on your application, the mechanism to store your resources may differ, nevertheless, the library comes bundle with a optional service which enables resolving domain name without the constant network overhead of continuously downloading the remote databases.

The interfaces and classes defined under the Pdp\Storage namespace enable integrating a resource managing system and provide an implementation example using PHP-FIG PSR interfaces.

Using PHP-FIG interfaces

The Pdp\Storage\PsrStorageFactory enables returning storage instances that retrieve, convert and cache the Public Suffix List and the IANA Top Level Domain List using standard interfaces published by the PHP-FIG.

To work as intended, the Pdp\Storage\PsrStorageFactory constructor requires:

  • a PSR-16 Simple Cache implementing library.
  • a PSR-17 HTTP Factory implementing library.
  • a PSR-18 HTTP Client implementing library.

When creating a new storage instance you will require:

  • a $cachePrefix argument to optionally add a prefix to your cache index, default to the empty string;
  • a $ttl argument if you need to set the default $ttl, default to null to use the underlying caching default TTL;

The $ttl argument can be:

  • an int representing time in second (see PSR-16);
  • a DateInterval object (see PSR-16);
  • a DateTimeInterface object representing the date and time when the item will expire;

The package does not provide any implementation of such interfaces as you can find robust and battle tested implementations on packagist.

Refreshing the resource using the provided factories



For the purpose of this example we will use our PSR powered solution with:

  • Guzzle HTTP Client as our PSR-18 HTTP client;
  • Guzzle PSR-7 package which provide factories to create a PSR-7 objects using PSR-17 interfaces;
  • Symfony Cache Component as our PSR-16 cache implementation provider;

We will cache both external sources for 24 hours in a PostgreSQL database.

You are free to use other libraries/solutions/settings as long as they implement the required PSR interfaces.


use GuzzleHttp\Psr7\Request;
use Pdp\Storage\PsrStorageFactory;
use Psr\Http\Message\RequestFactoryInterface;
use Psr\Http\Message\RequestInterface;
use Symfony\Component\Cache\Adapter\PdoAdapter;
use Symfony\Component\Cache\Psr16Cache;

$pdo = new PDO(
$cache = new Psr16Cache(new PdoAdapter($pdo, 'pdp', 43200));
$client = new GuzzleHttp\Client();
$requestFactory = new class implements RequestFactoryInterface {
    public function createRequest(string $method, $uri): RequestInterface
        return new Request($method, $uri);

$cachePrefix = 'pdp_';
$cacheTtl = new DateInterval('P1D');
$factory = new PsrStorageFactory($cache, $client, $requestFactory);
$pslStorage = $factory->createPublicSuffixListStorage($cachePrefix, $cacheTtl);
$rzdStorage = $factory->createTopLevelDomainListStorage($cachePrefix, $cacheTtl);

// if you need to force refreshing the rules 
// before calling them (to use in a refresh script)
// uncomment this part or adapt it to you script logic
// $pslStorage->delete(PsrStorageFactory::PUBLIC_SUFFIX_LIST_URI);
$publicSuffixList = $pslStorage->get(PsrStorageFactory::PUBLIC_SUFFIX_LIST_URI);

// if you need to force refreshing the rules 
// before calling them (to use in a refresh script)
// uncomment this part or adapt it to you script logic
// $rzdStorage->delete(PsrStorageFactory::TOP_LEVEL_DOMAIN_LIST_URI);
$topLevelDomains = $rzdStorage->get(PsrStorageFactory::TOP_LEVEL_DOMAIN_LIST_URI);


Be sure to adapt the following code to your own application. The following code is an example given without warranty of it working out of the box.


You should use your dependency injection container to avoid repeating this code in your application.

Automatic Updates

It is important to always have an up to date Public Suffix List and Top Level Domain List.
This library no longer provide an out of the box script to do so as implementing such a job heavily depends on your application setup. You can use the above example script as a starting point to implement such a job.


Please see CHANGELOG for more information about what has been changed since version 5.0.0 was released.


Contributions are welcome and will be fully credited. Please see CONTRIBUTING for details.


pdp-domain-parser has:

  • a PHPUnit test suite
  • a code analysis compliance test suite using PHPStan.
  • a coding style compliance test suite using PHP CS Fixer.

To run the tests, run the following command from the project folder.

$ composer test


If you discover any security related issues, please email instead of using the issue tracker.



The MIT License (MIT). Please see License File for more information.


Portions of the Pdp\Rules class are derivative works of the PHP registered-domain-libs. I've included a copy of the Apache Software Foundation License 2.0 in this project.