XUID library for PHP

v1.2.0 2019-04-18 12:40 UTC


XUIDs are URL-friendly compressed UUIDs

Why XUIDs?

A UUID v4 is a great choice as a primary key for your database tables.

But, they are quite long to use in URLs and databases : 32 alphanumeric characters and four hyphens (36 characters total)

A XUID is a UUID, converted into a 128-bit value, converted into a base64 string (stripped from padding characters), then converted into url-safe base64 (replacing + and / into - and _ respectively - custom mappings available, see below for more info).

This gives you a 22 character string, safe to use in URLs.

It also safely decodes into a full UUID string again.


  • Takes less space in database fields
  • Shorter URLs
  • Un-guessable primary keys in URLs


use Xuid\Xuid;

$xuid = new Xuid();

$in = $xuid->getUuid(); // ffe25f31-907e-46c0-b2f8-8bbfedb9082b

$tmp = $xuid->encode($in); // _-JfMZB-RsCy-Iu_7bkIKw

$out = $xuid->decode($tmp); // ffe25f31-907e-46c0-b2f8-8bbfedb9082b

$tmp = $xuid->getXuid();

$newXuid = $xuid->getXuid();
if (!$xuid->isValidXuid($newXuid)) {
    // this Xuid is valid

All methods can be called statically as well:

use Xuid\Xuid;

$x = Xuid::getXuid();
$u = Xuid::decode($x);


You'll find example code in the example/ directory.

To generate 100 XUIDs, run the following command:

php example/generate.php

Example output:

y9G-jWmYQcW5HyxiU_Pnew: cbd1be8d-6998-41c5-b91f-2c6253f3e77b
IOnEowPFR-G74hEBtTSJVQ: 20e9c4a3-03c5-47e1-bbe2-1101b5348955
Jgn4-Hs3STyNMC_ectX4kA: 2609f8f8-7b37-493c-8d30-2fde72d5f890
-rO6xKQFQCGPozxJf35lGw: fab3bac4-a405-4021-8fa3-3c497f7e651b
c6l3fR3mThSlL1OlNYgCvg: 73a9777d-1de6-4e14-a52f-53a5358802be
3PK9eo00T92z6oSsFNCY-A: dcf2bd7a-8d34-4fdd-b3ea-84ac14d098f8
vCMyGdkGT-m6e6m4BKcfgA: bc233219-d906-4fe9-ba7b-a9b804a71f80
JJ_1Ndd3S9SwG9urLr5NTQ: 249ff535-d777-4bd4-b01b-dbab2ebe4d4d
KSn-sn-cToydyfvjLZHhBA: 2929feb2-7f9c-4e8c-9dc9-fbe32d91e104
fi_nfoXrQ_GoYrzT4oZqRw: 7e2fe77e-85eb-43f1-a862-bcd3e2866a47
1vKKRSlHQICMj5X5iktHZA: d6f28a45-2947-4080-8c8f-95f98a4b4764
yWJ5VPsISbS46anoEO2HVQ: c9627954-fb08-49b4-b8e9-a9e810ed8755

Generatic alpha-numeric XUIDs only

- and _ are occassionally found in XUIDs. If you prefer alpha-numeric only XUIDs, simply call the following static method before generating your XUIDs:


This will keep generating XUIDs until one is found that only contains alphanumeric characters. That means that it could require two or more attempts before a valid XUID can be returned. In practice this does not add any noticable latency. But this is worth keeping in mind when generating XUIDs in bulk.

Custom character mappings

The default character mapping for XUIDs (url safe) is:

  • + => -
  • / => _

But you can apply any other mapping you want for any of the characters used in base64 encoding, by calling Xuid::map(). For example, you can create double-click safe XUIDs (the whole XUID is selectable simply by double clicking it), by mapping + and _ to selectable characters. For example:

        '+' => 'Æ',
        '/' => 'Ä',

echo Xuid::getXuid() . PHP_EOL; // Outputs a XUID such as `xQamÆ0kGSjepUAD1bÄ09kg`

Beware to only pass in URL safe characters if your use-case requires URL safe XUIDs.

PHPUnit tests

vendor/bin/phpunit test/

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