diff --git a/.distignore b/.distignore
index ab251165..3986af78 100755
--- a/.distignore
+++ b/.distignore
@@ -17,8 +17,9 @@ artifact
 composer.json
 composer.lock
 package-lock.json
-vendor/phpoffice/phpspreadsheet/samples
-vendor/phpoffice/phpspreadsheet/docs
+vendor/openspout/openspout/LICENSE-for-*
+vendor/openspout/openspout/UPGRADE-3.0.md
+vendor/openspout/openspout/README.md
 cypress
 cypress.json
 .github
diff --git a/classes/Visualizer/Module.php b/classes/Visualizer/Module.php
index 5604ea5d..8ef678c1 100644
--- a/classes/Visualizer/Module.php
+++ b/classes/Visualizer/Module.php
@@ -235,7 +235,6 @@ public function _getDataAs( $chart_id, $type ) {
 			}
 
 			$filename   = $title;
-
 			switch ( $type ) {
 				case 'csv':
 					$final   = $this->_getCSV( $rows, $filename, false );
@@ -324,9 +323,9 @@ private function _getCSV( $rows, $filename, $enclose ) {
 	 * @param string $filename The name of the file to use.
 	 */
 	private function _getExcel( $rows, $filename ) {
-		// PHPExcel did not like sheet names longer than 31 characters and we will assume the same with PhpSpreadsheet
-		$chart      = substr( $filename, 0, 30 );
-		$filename   .= '.xlsx';
+		// OpenSpout allows for long sheet names, but let's keep the same limit for compatibility.
+		$chart     = substr( $filename, 0, 30 );
+		$filename .= '.xlsx';
 		if ( ! apply_filters( 'vizualizer_export_include_series_type', true ) ) {
 			unset( $rows[1] );
 			$rows = array_values( $rows );
@@ -339,22 +338,32 @@ function( $r ) {
 		}
 		$vendor_file = VISUALIZER_ABSPATH . '/vendor/autoload.php';
 		if ( is_readable( $vendor_file ) ) {
-			include_once( $vendor_file );
-		}
-		$xlsData    = '';
-		if ( class_exists( 'PhpOffice\PhpSpreadsheet\Spreadsheet' ) ) {
-			$doc        = new PhpOffice\PhpSpreadsheet\Spreadsheet();
-			$doc->getActiveSheet()->fromArray( $rows, null, 'A1' );
-			$doc->getActiveSheet()->setTitle( sanitize_title( $chart ) );
-			$doc        = apply_filters( 'visualizer_excel_doc', $doc );
-			$writer = PhpOffice\PhpSpreadsheet\IOFactory::createWriter( $doc, 'Xlsx' );
-			ob_start();
-			$writer->save( 'php://output' );
-			$xlsData = ob_get_contents();
-			ob_end_clean();
+			include_once $vendor_file;
+		}
+		$xlsData = '';
+		if ( class_exists( 'OpenSpout\Writer\Common\Creator\WriterEntityFactory' ) ) {
+			try {
+				// Use OpenSpout to create the XLSX file in memory.
+				$writer = \OpenSpout\Writer\Common\Creator\WriterEntityFactory::createXLSXWriter();
+				$writer->openToFile( 'php://output' ); // Open to output instead of a file.
+				$writer->getCurrentSheet()->setName( sanitize_title( $chart ) );
+
+				// Write rows.
+				foreach ( $rows as $row ) {
+					$rowFromValues = \OpenSpout\Writer\Common\Creator\WriterEntityFactory::createRowFromArray( $row );
+					$writer->addRow( $rowFromValues );
+				}
+
+				ob_start();
+				$writer->close(); // Saves and closes the file in the output buffer.
+				$xlsData = ob_get_clean();
+			} catch ( Exception $e ) {
+				do_action( 'themeisle_log_event', Visualizer_Plugin::NAME, 'OpenSpout writer error: ' . $e->getMessage(), 'error', __FILE__, __LINE__ );
+				error_log( 'OpenSpout writer error: ' . $e->getMessage() );
+			}
 		} else {
-			do_action( 'themeisle_log_event', Visualizer_Plugin::NAME, 'Class PhpOffice\PhpSpreadsheet\Spreadsheet does not exist!', 'error', __FILE__, __LINE__ );
-			error_log( 'Class PhpOffice\PhpSpreadsheet\Spreadsheet does not exist!' );
+			do_action( 'themeisle_log_event', Visualizer_Plugin::NAME, 'Class OpenSpout\Writer\Common\Creator\WriterEntityFactory does not exist!', 'error', __FILE__, __LINE__ );
+			error_log( 'Class OpenSpout\Writer\Common\Creator\WriterEntityFactory does not exist!' );
 		}
 		return array(
 			'csv'  => 'data:application/vnd.ms-excel;base64,' . base64_encode( $xlsData ),
diff --git a/classes/Visualizer/Render/Sidebar.php b/classes/Visualizer/Render/Sidebar.php
index 5f8cbb9f..702d1a69 100644
--- a/classes/Visualizer/Render/Sidebar.php
+++ b/classes/Visualizer/Render/Sidebar.php
@@ -270,7 +270,7 @@ private static function is_excel_enabled() {
 			return false;
 		}
 
-		return class_exists( 'PhpOffice\PhpSpreadsheet\Spreadsheet' ) && extension_loaded( 'zip' ) && extension_loaded( 'xml' ) && extension_loaded( 'fileinfo' );
+		return class_exists( 'OpenSpout\Writer\Common\Creator\WriterEntityFactory' ) && extension_loaded( 'zip' ) && extension_loaded( 'xml' ) && extension_loaded( 'fileinfo' );
 	}
 
 	/**
diff --git a/composer.json b/composer.json
index 87179b8b..bfa3e1a2 100644
--- a/composer.json
+++ b/composer.json
@@ -22,13 +22,12 @@
   },
   "require": {
     "codeinwp/themeisle-sdk": "^3.3",
-    "phpoffice/phpspreadsheet": "1.8.2",
-    "neitanod/forceutf8": "~2.0"
+    "neitanod/forceutf8": "~2.0",
+    "openspout/openspout": "^3.7"
   },
   "autoload": {
     "files": [
-      "vendor/codeinwp/themeisle-sdk/load.php",
-      "vendor/phpoffice/phpspreadsheet/src/Bootstrap.php"
+      "vendor/codeinwp/themeisle-sdk/load.php"
     ]
   },
   "scripts": {
@@ -40,7 +39,7 @@
   "config": {
     "optimize-autoloader": true,
     "platform": {
-      "php": "5.6"
+      "php": "7.4"
     },
     "allow-plugins": {
       "dealerdirect/phpcodesniffer-composer-installer": true
diff --git a/composer.lock b/composer.lock
index a191b6c6..07868713 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "b1c4972cf7a69e915c83661005512e70",
+    "content-hash": "7000266e616112b1392930052784add1",
     "packages": [
         {
             "name": "codeinwp/themeisle-sdk",
@@ -47,170 +47,6 @@
             },
             "time": "2024-10-25T07:28:34+00:00"
         },
-        {
-            "name": "markbaker/complex",
-            "version": "1.5.0",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/MarkBaker/PHPComplex.git",
-                "reference": "c3131244e29c08d44fefb49e0dd35021e9e39dd2"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/MarkBaker/PHPComplex/zipball/c3131244e29c08d44fefb49e0dd35021e9e39dd2",
-                "reference": "c3131244e29c08d44fefb49e0dd35021e9e39dd2",
-                "shasum": ""
-            },
-            "require": {
-                "php": "^5.6.0|^7.0"
-            },
-            "require-dev": {
-                "dealerdirect/phpcodesniffer-composer-installer": "^0.5.0",
-                "phpcompatibility/php-compatibility": "^9.0",
-                "phpdocumentor/phpdocumentor": "2.*",
-                "phploc/phploc": "^4.0|^5.0|^6.0|^7.0",
-                "phpmd/phpmd": "2.*",
-                "phpunit/phpunit": "^4.8.35|^5.0|^6.0|^7.0",
-                "sebastian/phpcpd": "2.*",
-                "squizlabs/php_codesniffer": "^3.4.0"
-            },
-            "type": "library",
-            "autoload": {
-                "files": [
-                    "classes/src/functions/abs.php",
-                    "classes/src/functions/acos.php",
-                    "classes/src/functions/acosh.php",
-                    "classes/src/functions/acot.php",
-                    "classes/src/functions/acoth.php",
-                    "classes/src/functions/acsc.php",
-                    "classes/src/functions/acsch.php",
-                    "classes/src/functions/argument.php",
-                    "classes/src/functions/asec.php",
-                    "classes/src/functions/asech.php",
-                    "classes/src/functions/asin.php",
-                    "classes/src/functions/asinh.php",
-                    "classes/src/functions/atan.php",
-                    "classes/src/functions/atanh.php",
-                    "classes/src/functions/conjugate.php",
-                    "classes/src/functions/cos.php",
-                    "classes/src/functions/cosh.php",
-                    "classes/src/functions/cot.php",
-                    "classes/src/functions/coth.php",
-                    "classes/src/functions/csc.php",
-                    "classes/src/functions/csch.php",
-                    "classes/src/functions/exp.php",
-                    "classes/src/functions/inverse.php",
-                    "classes/src/functions/ln.php",
-                    "classes/src/functions/log2.php",
-                    "classes/src/functions/log10.php",
-                    "classes/src/functions/negative.php",
-                    "classes/src/functions/pow.php",
-                    "classes/src/functions/rho.php",
-                    "classes/src/functions/sec.php",
-                    "classes/src/functions/sech.php",
-                    "classes/src/functions/sin.php",
-                    "classes/src/functions/sinh.php",
-                    "classes/src/functions/sqrt.php",
-                    "classes/src/functions/tan.php",
-                    "classes/src/functions/tanh.php",
-                    "classes/src/functions/theta.php",
-                    "classes/src/operations/add.php",
-                    "classes/src/operations/subtract.php",
-                    "classes/src/operations/multiply.php",
-                    "classes/src/operations/divideby.php",
-                    "classes/src/operations/divideinto.php"
-                ],
-                "psr-4": {
-                    "Complex\\": "classes/src/"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Mark Baker",
-                    "email": "mark@lange.demon.co.uk"
-                }
-            ],
-            "description": "PHP Class for working with complex numbers",
-            "homepage": "https://github.com/MarkBaker/PHPComplex",
-            "keywords": [
-                "complex",
-                "mathematics"
-            ],
-            "time": "2020-08-26T19:47:57+00:00"
-        },
-        {
-            "name": "markbaker/matrix",
-            "version": "1.2.3",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/MarkBaker/PHPMatrix.git",
-                "reference": "44bb1ab01811116f01fe216ab37d921dccc6c10d"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/MarkBaker/PHPMatrix/zipball/44bb1ab01811116f01fe216ab37d921dccc6c10d",
-                "reference": "44bb1ab01811116f01fe216ab37d921dccc6c10d",
-                "shasum": ""
-            },
-            "require": {
-                "php": "^5.6.0|^7.0.0"
-            },
-            "require-dev": {
-                "dealerdirect/phpcodesniffer-composer-installer": "dev-master",
-                "phpcompatibility/php-compatibility": "dev-master",
-                "phploc/phploc": "^4",
-                "phpmd/phpmd": "dev-master",
-                "phpunit/phpunit": "^5.7|^6.0|7.0",
-                "sebastian/phpcpd": "^3.0",
-                "squizlabs/php_codesniffer": "^3.0@dev"
-            },
-            "type": "library",
-            "autoload": {
-                "files": [
-                    "classes/src/Functions/adjoint.php",
-                    "classes/src/Functions/antidiagonal.php",
-                    "classes/src/Functions/cofactors.php",
-                    "classes/src/Functions/determinant.php",
-                    "classes/src/Functions/diagonal.php",
-                    "classes/src/Functions/identity.php",
-                    "classes/src/Functions/inverse.php",
-                    "classes/src/Functions/minors.php",
-                    "classes/src/Functions/trace.php",
-                    "classes/src/Functions/transpose.php",
-                    "classes/src/Operations/add.php",
-                    "classes/src/Operations/directsum.php",
-                    "classes/src/Operations/subtract.php",
-                    "classes/src/Operations/multiply.php",
-                    "classes/src/Operations/divideby.php",
-                    "classes/src/Operations/divideinto.php"
-                ],
-                "psr-4": {
-                    "Matrix\\": "classes/src/"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Mark Baker",
-                    "email": "mark@lange.demon.co.uk"
-                }
-            ],
-            "description": "PHP Class for working with matrices",
-            "homepage": "https://github.com/MarkBaker/PHPMatrix",
-            "keywords": [
-                "mathematics",
-                "matrix",
-                "vector"
-            ],
-            "time": "2021-01-26T14:36:01+00:00"
-        },
         {
             "name": "neitanod/forceutf8",
             "version": "v2.0.4",
@@ -249,146 +85,93 @@
             "time": "2019-12-10T14:09:14+00:00"
         },
         {
-            "name": "phpoffice/phpspreadsheet",
-            "version": "1.8.2",
+            "name": "openspout/openspout",
+            "version": "v3.7.4",
             "source": {
                 "type": "git",
-                "url": "https://github.com/PHPOffice/PhpSpreadsheet.git",
-                "reference": "0c1346a1956347590b7db09533966307d20cb7cc"
+                "url": "https://github.com/openspout/openspout.git",
+                "reference": "dfbbd53b5edcd486b45a37f6a04fac33073c70f3"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/PHPOffice/PhpSpreadsheet/zipball/0c1346a1956347590b7db09533966307d20cb7cc",
-                "reference": "0c1346a1956347590b7db09533966307d20cb7cc",
+                "url": "https://api.github.com/repos/openspout/openspout/zipball/dfbbd53b5edcd486b45a37f6a04fac33073c70f3",
+                "reference": "dfbbd53b5edcd486b45a37f6a04fac33073c70f3",
                 "shasum": ""
             },
             "require": {
-                "ext-ctype": "*",
                 "ext-dom": "*",
-                "ext-fileinfo": "*",
-                "ext-gd": "*",
-                "ext-iconv": "*",
+                "ext-filter": "*",
                 "ext-libxml": "*",
-                "ext-mbstring": "*",
-                "ext-simplexml": "*",
-                "ext-xml": "*",
                 "ext-xmlreader": "*",
-                "ext-xmlwriter": "*",
                 "ext-zip": "*",
-                "ext-zlib": "*",
-                "markbaker/complex": "^1.4",
-                "markbaker/matrix": "^1.1",
-                "php": "^5.6|^7.0",
-                "psr/simple-cache": "^1.0"
+                "php": "~7.3.0 || ~7.4.0 || ~8.0.0 || ~8.1.0"
             },
             "require-dev": {
-                "doctrine/instantiator": "^1.0.0",
-                "dompdf/dompdf": "^0.8.0",
-                "friendsofphp/php-cs-fixer": "@stable",
-                "jpgraph/jpgraph": "^4.0",
-                "mpdf/mpdf": "^7.0.0",
-                "phpcompatibility/php-compatibility": "^8.0",
-                "phpunit/phpunit": "^5.7",
-                "squizlabs/php_codesniffer": "^3.3",
-                "tecnickcom/tcpdf": "^6.2"
+                "ext-zlib": "*",
+                "friendsofphp/php-cs-fixer": "^3.4",
+                "phpstan/phpstan": "^1.4",
+                "phpstan/phpstan-phpunit": "^1.0",
+                "phpunit/phpunit": "^9.5"
             },
             "suggest": {
-                "dompdf/dompdf": "Option for rendering PDF with PDF Writer",
-                "jpgraph/jpgraph": "Option for rendering charts, or including charts with PDF or HTML Writers",
-                "mpdf/mpdf": "Option for rendering PDF with PDF Writer",
-                "tecnickcom/tcpdf": "Option for rendering PDF with PDF Writer"
+                "ext-iconv": "To handle non UTF-8 CSV files (if \"php-intl\" is not already installed or is too limited)",
+                "ext-intl": "To handle non UTF-8 CSV files (if \"iconv\" is not already installed)"
             },
             "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.3.x-dev"
+                }
+            },
             "autoload": {
                 "psr-4": {
-                    "PhpOffice\\PhpSpreadsheet\\": "src/PhpSpreadsheet"
+                    "OpenSpout\\": "src/"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
-                "LGPL-2.1-or-later"
+                "MIT"
             ],
             "authors": [
                 {
-                    "name": "Erik Tilt"
-                },
-                {
-                    "name": "Adrien Crivelli"
-                },
-                {
-                    "name": "Maarten Balliauw",
-                    "homepage": "https://blog.maartenballiauw.be"
-                },
-                {
-                    "name": "Mark Baker",
-                    "homepage": "https://markbakeruk.net"
-                },
-                {
-                    "name": "Franck Lefevre",
-                    "homepage": "https://rootslabs.net"
+                    "name": "Adrien Loison",
+                    "email": "adrien@box.com"
                 }
             ],
-            "description": "PHPSpreadsheet - Read, Create and Write Spreadsheet documents in PHP - Spreadsheet engine",
-            "homepage": "https://github.com/PHPOffice/PhpSpreadsheet",
+            "description": "PHP Library to read and write spreadsheet files (CSV, XLSX and ODS), in a fast and scalable way",
+            "homepage": "https://github.com/openspout/openspout",
             "keywords": [
-                "OpenXML",
+                "OOXML",
+                "csv",
                 "excel",
-                "gnumeric",
+                "memory",
+                "odf",
                 "ods",
+                "office",
+                "open",
                 "php",
+                "read",
+                "scale",
                 "spreadsheet",
-                "xls",
+                "stream",
+                "write",
                 "xlsx"
             ],
-            "time": "2019-07-08T21:21:25+00:00"
-        },
-        {
-            "name": "psr/simple-cache",
-            "version": "1.0.1",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/php-fig/simple-cache.git",
-                "reference": "408d5eafb83c57f6365a3ca330ff23aa4a5fa39b"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/php-fig/simple-cache/zipball/408d5eafb83c57f6365a3ca330ff23aa4a5fa39b",
-                "reference": "408d5eafb83c57f6365a3ca330ff23aa4a5fa39b",
-                "shasum": ""
-            },
-            "require": {
-                "php": ">=5.3.0"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "1.0.x-dev"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Psr\\SimpleCache\\": "src/"
-                }
+            "support": {
+                "issues": "https://github.com/openspout/openspout/issues",
+                "source": "https://github.com/openspout/openspout/tree/v3.7.4"
             },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
+            "funding": [
+                {
+                    "url": "https://paypal.me/filippotessarotto",
+                    "type": "custom"
+                },
                 {
-                    "name": "PHP-FIG",
-                    "homepage": "http://www.php-fig.org/"
+                    "url": "https://github.com/Slamdunk",
+                    "type": "github"
                 }
             ],
-            "description": "Common interfaces for simple caching",
-            "keywords": [
-                "cache",
-                "caching",
-                "psr",
-                "psr-16",
-                "simple-cache"
-            ],
-            "time": "2017-10-23T01:57:42+00:00"
+            "time": "2022-03-31T06:15:15+00:00"
         }
     ],
     "packages-dev": [
@@ -805,7 +588,7 @@
     "platform": [],
     "platform-dev": [],
     "platform-overrides": {
-        "php": "5.6"
+        "php": "7.4"
     },
-    "plugin-api-version": "2.6.0"
+    "plugin-api-version": "2.3.0"
 }