Several maintained forks exist on GitHub. This is often the best place for modern versions compatible with PHP 8.
Since the PHP QR Code library is open-source (LGPL licensed), you should only download it from verified repositories to ensure the code is clean and up to date.
This is the official original home of the project. Search for "PHP QR Code" to find the full package containing qrlib.php .
For legacy or shared hosting environments where Composer is unavailable, qrlib.php remains the best free download. For new projects, consider endroid/qr-code via Composer.
lasalesi/phpqrcode: PHP library to produce QR Codes - GitHub