PHPExcel - OpenXML - Read, Create and Write Spreadsheet documents in PHP - Spreadsheet engine
PHPExcel last version, 1.8.1, was released in 2015. The project is no longer maintained and should not be used anymore.
All users should migrate to its direct successor PhpSpreadsheet, or another alternative.
In a few months, the GitHub project will be marked as archived, so everything will be read-only.
PHPExcel is licensed under LGPL (GNU LESSER GENERAL PUBLIC LICENSE)