I have recently finished rewriting Multiavatar Generator in PHP.
Source code: https://github.com/multiavatar/multiavatar-php
Initially coded in JavaScript, this version of Multiavatar is for PHP-based backend environments.
It is now being used for the Multiavatar API (https://api.multiavatar.com), which became much faster, because before it was a mix of PHP and Node.js, and now just PHP.
You can use it by including the Multiavatar.php in your code, or by installing it with Composer.
More info about the Multiavatar algorithm and design is available in the JS repository (https://github.com/multiavatar/Multiavatar) and in the Multiavatar web-app (https://multiavatar.com), which is based on Laravel 8, Vue.js, and ImageMagick PHP extension.
Your feedback is welcome and appreciated!