PhpSpreadsheet
A pure PHP library for reading and writing spreadsheet files
... PhpSpreadsheet into your project. Or also download the documentation and samples if you plan to use them. A good way to get started is to run some of the samples. Don't forget to download them via --prefer-source composer flag. And then serve them via PHP built-in webserver. PhpSpreadsheet relies on Composer autoloader. So before working with PhpSpreadsheet in standalone, be sure to run composer install.