Spreadsheets, driven by code.

<?php

require 'vendor/autoload.php';

use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;
use PhpOffice\PhpSpreadsheet\Writer\Xls;
use PhpOffice\PhpSpreadsheet\Writer\Ods;

// Build ONE spreadsheet object. Nothing on it is tied to a file format.
$spreadsheet = new Spreadsheet();
$worksheet = $spreadsheet->getActiveSheet();
$worksheet->setTitle('Report');

$worksheet->fromArray([
    ['Region', 'Units', 'Revenue'],
    ['North', 120, 4800],
    ['South', 90, 3600],
    ['East', 150, 6000],
], null, 'A1');

$worksheet->getStyle('A1:C1')->getFont()->setBold(true);
$worksheet->getStyle('C2:C4')->getNumberFormat()->setFormatCode('$#,##0');

// The SAME object, saved through three writers. Binary .xls before .ods.
(new Xlsx($spreadsheet))->save('report.xlsx');
(new Xls($spreadsheet))->save('report.xls');
(new Ods($spreadsheet))->save('report.ods');

foreach (['report.xlsx', 'report.xls', 'report.ods'] as $file) {
    printf("%-12s %6d bytes\n", $file, filesize($file));
}