A PHP library for generating RFC 4122 version 1, 2, 3, 4, and 5 universally unique identifiers (UUID).

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4.0.0-alpha1 2020-01-22 06:41 UTC


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ramsey/uuid is a PHP library for generating and working with RFC 4122 version 1, 2, 3, 4, and 5 universally unique identifiers (UUID).

This project adheres to a Contributor Code of Conduct. By participating in this project and its community, you are expected to uphold this code.

From Wikipedia:

The intent of UUIDs is to enable distributed systems to uniquely identify information without significant central coordination. In this context the word unique should be taken to mean "practically unique" rather than "guaranteed unique". Since the identifiers have a finite size, it is possible for two differing items to share the same identifier. The identifier size and generation process need to be selected so as to make this sufficiently improbable in practice. Anyone can create a UUID and use it to identify something with reasonable confidence that the same identifier will never be unintentionally created by anyone to identify something else. Information labeled with UUIDs can therefore be later combined into a single database without needing to resolve identifier (ID) conflicts.

Much inspiration for this library came from the Java and Python UUID libraries.


The preferred method of installation is via Composer. Run the following command to install the package and add it as a requirement to your project's composer.json:

composer require ramsey/uuid

Upgrading from 3.x to 4.x

This section is a draft. It is incomplete.

In the 4.x series, the following methods will always return strings:

  • UuidInterface::getInteger()
  • Uuid::getTimeLow()
  • Uuid::getTimeMid()
  • Uuid::getTimeHiAndVersion()
  • Uuid::getClockSequence()
  • Uuid::getClockSeqHiAndReserved()
  • Uuid::getClockSeqLow()
  • Uuid::getNode()
  • Uuid::getLeastSignificantBits()
  • Uuid::getMostSignificantBits()

In 3.x, these methods returned varying types, depending on the environment: int, string, or Moontoast\Math\BigNumber. Moving to a string return type provides you with the flexibility to use the arbitrary-precision arithmetic library of your choice (i.e., bcmath, gmp, moontoast/math, phpseclib/phpseclib, brick/math, etc.).

While still on the ramsey/uuid 3.x series, you may ease this transition by casting the return value these methods to a string and passing the result to a Moontoast\Math\BigNumber object (if already using moontoast/math) or transitioning to brick/math, etc. For example:

$bigNumber = new \Moontoast\Math\BigNumber($uuid->getInteger()->toString());

// or

$bigInteger = \Brick\Math\BigInteger::of($uuid->getInteger()->toString());

In 4.x, Uuid::getFields() returns an instance of Fields\FieldsInterface. Previously, it returned an array of integer values (on 64-bit systems only).

For methods of Fields\FieldsInterface that return UUID fields (e.g. getTimeLow(), getNode(), etc.) use the return type Type\Hexadecimal. If you need the integer values for these fields, we recommend using the arbitrary-precision library of your choice (i.e., bcmath, gmp, brick/math, etc.) to convert them. Each is an unsigned integer, and some fields (time low, and node) are large enough that they will overflow the system's max integer values, so arbitrary-precision arithmetic is necessary to operate on them.

For example, you may choose brick/math to convert the node field to a string integer:

// This works only in ramsey/uuid 4.x.
$bigInteger = \Brick\Math\BigInteger::fromBase($uuid->getFields()->getNode(), 16);

While still on the ramsey/uuid 3.x series, you may ease this transition by building an array like this:

use Brick\Math\BigInteger;

$fields = [
    'time_low' => (string) BigInteger::fromBase($uuid->getTimeLowHex(), 16),
    'time_mid' => (string) BigInteger::fromBase($uuid->getTimeMidHex(), 16),
    'time_hi_and_version' => (string) BigInteger::fromBase($uuid->getTimeHiAndVersionHex(), 16),
    'clock_seq_hi_and_reserved' => (string) BigInteger::fromBase($uuid->getClockSeqHiAndReservedHex(), 16),
    'clock_seq_low' => (string) BigInteger::fromBase($uuid->getClockSeqLowHex(), 16),
    'node' => (string) BigInteger::fromBase($uuid->getNodeHex(), 16),

Upgrading from 2.x to 3.x

While we have made significant internal changes to the library, we have made every effort to ensure a seamless upgrade path from the 2.x series of this library to 3.x.

One major breaking change is the transition from the Rhumsaa root namespace to Ramsey. In most cases, all you will need is to change the namespace to Ramsey in your code, and everything will "just work."

Here are full details on the breaking changes to the public API of this library:

  1. All namespace references of Rhumsaa have changed to Ramsey. Simply change the namespace to Ramsey in your code and everything should work.
  2. The console application has moved to ramsey/uuid-console. If using the console functionality, use Composer to require ramsey/uuid-console.
  3. The Doctrine field type mapping has moved to ramsey/uuid-doctrine. If using the Doctrine functionality, use Composer to require ramsey/uuid-doctrine.

What to do if you see a "rhumsaa/uuid is abandoned" message

When installing your project's dependencies using Composer, you might see the following message:

Package rhumsaa/uuid is abandoned, you should avoid using it. Use
ramsey/uuid instead.

Don't panic. Simply execute the following commands with Composer:

composer remove rhumsaa/uuid
composer require ramsey/uuid=^2.9

After doing so, you will have the latest ramsey/uuid package in the 2.x series, and there will be no need to modify any code; the namespace in the 2.x series is still Rhumsaa.


See the cookbook on the wiki for more examples and approaches to specific use-cases.

require 'vendor/autoload.php';

use Ramsey\Uuid\Uuid;
use Ramsey\Uuid\Exception\UnsatisfiedDependencyException;

try {

    // Generate a version 1 (time-based) UUID object
    $uuid1 = Uuid::uuid1();
    echo $uuid1->toString() . "\n"; // i.e. e4eaaaf2-d142-11e1-b3e4-080027620cdd

    // Generate a version 3 (name-based and hashed with MD5) UUID object
    $uuid3 = Uuid::uuid3(Uuid::NAMESPACE_DNS, 'php.net');
    echo $uuid3->toString() . "\n"; // i.e. 11a38b9a-b3da-360f-9353-a5a725514269

    // Generate a version 4 (random) UUID object
    $uuid4 = Uuid::uuid4();
    echo $uuid4->toString() . "\n"; // i.e. 25769c6c-d34d-4bfe-ba98-e0ee856f3e7a

    // Generate a version 5 (name-based and hashed with SHA1) UUID object
    $uuid5 = Uuid::uuid5(Uuid::NAMESPACE_DNS, 'php.net');
    echo $uuid5->toString() . "\n"; // i.e. c4a760a8-dbcf-5254-a0d9-6a4474bd1b62

} catch (UnsatisfiedDependencyException $e) {

    // Some dependency was not met. Either the method cannot be called on a
    // 32-bit system, or it can, but it relies on Moontoast\Math to be present.
    echo 'Caught exception: ' . $e->getMessage() . "\n";



Contributions are welcome! Please read CONTRIBUTING.md for details.

Copyright and License

The ramsey/uuid library is copyright © Ben Ramsey and licensed for use under the MIT License (MIT). Please see LICENSE for more information.