diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..aa2f745
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,13 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: monthly
+
+    # Group all dependabot version update PRs into one
+    groups:
+      github-actions:
+        applies-to: version-updates
+        patterns:
+          - "*"
diff --git a/.github/workflows/node.js.yml b/.github/workflows/node.js.yml
index a97a874..b2107fb 100644
--- a/.github/workflows/node.js.yml
+++ b/.github/workflows/node.js.yml
@@ -15,19 +15,19 @@ jobs:
         NODE_VERSION: [18.x, 20.x, 22.x]
     steps:
     - name: Checkout
-      uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+      uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
 
-    - name: Install xsltproc
+    - name: Install xsltproc & ImageMagick
       run: |
-        sudo apt-get install xsltproc
+        sudo apt-get install xsltproc imagemagick
 
     - name: Use Node.js ${{ matrix.NODE_VERSION }}
-      uses: actions/setup-node@1e60f620b9541d16bece96c5465dc8ee9832be0b # v4.0.3
+      uses: actions/setup-node@1d0ff469b7ec7b3cb9d8673fde0c81c44821de2a # v4.2.0
       with:
         node-version: ${{ matrix.NODE_VERSION }}
 
     - name: Cache
-      uses: actions/cache@0c45773b623bea8c8e75f6c82b208c3cf94ea4f9 # v4.0.2
+      uses: actions/cache@d4323d4df104b026a6aa633fdb11d772146be0bf # v4.2.2
       with:
         path: ~/.npm
         key: ${{ runner.os }}-node-${{ matrix.NODE_VERSION }}-npm-lock-${{ hashFiles('**/package-lock.json') }}
diff --git a/Gruntfile.js b/Gruntfile.js
index d49e922..e664603 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -11,7 +11,6 @@ grunt.loadNpmTasks( "grunt-check-modules" );
 grunt.loadNpmTasks( "grunt-contrib-clean" );
 grunt.loadNpmTasks( "grunt-contrib-copy" );
 grunt.loadNpmTasks( "grunt-contrib-handlebars" );
-grunt.loadNpmTasks( "grunt-contrib-uglify" );
 grunt.loadNpmTasks( "grunt-eslint" );
 
 grunt.initConfig( {
@@ -61,10 +60,7 @@ grunt.initConfig( {
 			dest: "app/dist"
 		}
 	},
-	uglify: {
-		options: {
-			preserveComments: "some"
-		},
+	minify: {
 
 		// DownloadBuilder minified frontend bundle
 		download: {
@@ -87,6 +83,9 @@ grunt.initConfig( {
 	}
 } );
 
+// local tasks
+grunt.loadTasks( "grunt-tasks" );
+
 function log( callback, successMsg, errorMsg ) {
 	return function( error, result, code ) {
 		if ( error && errorMsg ) {
@@ -279,7 +278,7 @@ function buildPackages( folder, callback ) {
 
 grunt.registerTask( "default", [ "check-modules", "eslint", "test" ] );
 
-grunt.registerTask( "build-app", [ "clean", "handlebars", "copy", "uglify" ] );
+grunt.registerTask( "build-app", [ "clean", "handlebars", "copy", "minify" ] );
 
 grunt.registerTask( "build-packages", "Builds zip package of each jQuery UI release specified in config file with all components and lightness theme, inside the given folder", function( folder ) {
 	var done = this.async();
diff --git a/grunt-tasks/minify.js b/grunt-tasks/minify.js
new file mode 100644
index 0000000..dfe37f5
--- /dev/null
+++ b/grunt-tasks/minify.js
@@ -0,0 +1,26 @@
+"use strict";
+
+const swc = require( "@swc/core" );
+const swcOptions = require( "../lib/swc-options" );
+
+module.exports = function( grunt ) {
+
+grunt.registerMultiTask( "minify", async function() {
+	const done = this.async();
+
+	for ( const file of this.files ) {
+		const contents = file.src
+			.map( singleFile => grunt.file.read( singleFile ) )
+			.join( "\n" );
+
+		const { code } = await swc.minify( contents, swcOptions );
+
+		grunt.file.write( file.dest, code );
+
+		grunt.log.writeln( `File ${ file.dest } created.` );
+	}
+
+	done();
+} );
+
+};
diff --git a/lib/jquery-ui-files.js b/lib/jquery-ui-files.js
index 0d762b2..12a6450 100644
--- a/lib/jquery-ui-files.js
+++ b/lib/jquery-ui-files.js
@@ -5,7 +5,8 @@ var stripBanner, glob, noDirectory,
 	fs = require( "node:fs" ),
 	path = require( "node:path" ),
 	sqwish = require( "sqwish" ),
-	UglifyJS = require( "uglify-js" ),
+	swc = require( "@swc/core" ),
+	swcOptions = require( "./swc-options" ),
 	util = require( "./util" ),
 	Files = require( "./files" ),
 	filesCache = {};
@@ -91,7 +92,10 @@ JqueryUiFiles.prototype = {
 				path: file.path.replace( /\.([^.]*)$/, ".min.$1" )
 			};
 			if ( ( /\.js$/i ).test( file.path ) ) {
-				minified[ file.path ].data = UglifyJS.minify( file.data.toString( "utf8" ) ).code;
+				minified[ file.path ].data = swc.minifySync(
+					file.data.toString( "utf8" ),
+					swcOptions
+				).code;
 			} else if ( ( /\.css$/i ).test( file.path ) ) {
 				minified[ file.path ].data = sqwish.minify( file.data.toString( "utf8" ) );
 			}
diff --git a/lib/package.js b/lib/package.js
index ff35e2c..0cf03dc 100644
--- a/lib/package.js
+++ b/lib/package.js
@@ -11,7 +11,8 @@ var indexTemplate,
 	sqwish = require( "sqwish" ),
 	ThemeRoller = require( "./themeroller" ),
 	semver = require( "semver" ),
-	UglifyJS = require( "uglify-js" );
+	swc = require( "@swc/core" ),
+	swcOptions = require( "./swc-options" );
 
 indexTemplate = handlebars.compile( fs.readFileSync( __dirname + "/../template/zip/index.html", "utf8" ) );
 
@@ -340,13 +341,8 @@ extend( Package.prototype, {
 		}
 
 		this.jsBundle.promise.then( function( js ) {
-			var minJs;
 			var _banner = banner( pkgJson, jsFileNames, { minify: true } );
-			var uglifyResult = UglifyJS.minify( js );
-			if ( uglifyResult.error ) {
-				throw uglifyResult.error;
-			}
-			minJs = uglifyResult.code;
+			var minJs = swc.minifySync( js, swcOptions ).code;
 			callback( null, _banner + minJs );
 		} ).catch( callback );
 	},
diff --git a/lib/swc-options.js b/lib/swc-options.js
new file mode 100644
index 0000000..b48807f
--- /dev/null
+++ b/lib/swc-options.js
@@ -0,0 +1,21 @@
+"use strict";
+
+module.exports = {
+	compress: {
+		ecma: 5,
+		hoist_funs: false,
+		loops: false
+	},
+	format: {
+		ecma: 5,
+		asciiOnly: true,
+
+		// That only preserves license comments.
+		// See https://swc.rs/docs/configuration/minification#note-about-comments
+		comments: true
+	},
+	inlineSourcesContent: false,
+	mangle: true,
+	module: false,
+	sourceMap: false
+};
diff --git a/package-lock.json b/package-lock.json
index 428011b..97226e2 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,9 +9,11 @@
 			"version": "2.3.13",
 			"license": "MIT",
 			"dependencies": {
+				"@swc/core": "1.11.5",
 				"async": "3.2.6",
 				"builder-amd": "0.0.3",
 				"builder-jquery-css": "0.0.4",
+				"eslint": "9.21.0",
 				"eslint-config-jquery": "3.0.2",
 				"express": "^4.21.2",
 				"fast-glob": "^3.3.3",
@@ -23,7 +25,6 @@
 				"grunt-contrib-clean": "2.0.1",
 				"grunt-contrib-copy": "1.0.0",
 				"grunt-contrib-handlebars": "3.0.0",
-				"grunt-contrib-uglify": "5.2.2",
 				"grunt-eslint": "25.0.0",
 				"handlebars": "4.7.8",
 				"lzma": "2.3.2",
@@ -31,7 +32,6 @@
 				"qunit": "^2.24.1",
 				"semver": "^7.7.1",
 				"sqwish": "0.2.2",
-				"uglify-js": "3.19.3",
 				"winston": "^3.17.0",
 				"wolfy87-eventemitter": "5.2.9"
 			},
@@ -431,6 +431,219 @@
 				"node": ">=14"
 			}
 		},
+		"node_modules/@swc/core": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core/-/core-1.11.5.tgz",
+			"integrity": "sha512-EVY7zfpehxhTZXOfy508gb3D78ihoGGmvyiTWtlBPjgIaidP1Xw0naHMD78CWiFlZmeDjKXJufGtsEGOnZdmNA==",
+			"hasInstallScript": true,
+			"license": "Apache-2.0",
+			"dependencies": {
+				"@swc/counter": "^0.1.3",
+				"@swc/types": "^0.1.19"
+			},
+			"engines": {
+				"node": ">=10"
+			},
+			"funding": {
+				"type": "opencollective",
+				"url": "https://opencollective.com/swc"
+			},
+			"optionalDependencies": {
+				"@swc/core-darwin-arm64": "1.11.5",
+				"@swc/core-darwin-x64": "1.11.5",
+				"@swc/core-linux-arm-gnueabihf": "1.11.5",
+				"@swc/core-linux-arm64-gnu": "1.11.5",
+				"@swc/core-linux-arm64-musl": "1.11.5",
+				"@swc/core-linux-x64-gnu": "1.11.5",
+				"@swc/core-linux-x64-musl": "1.11.5",
+				"@swc/core-win32-arm64-msvc": "1.11.5",
+				"@swc/core-win32-ia32-msvc": "1.11.5",
+				"@swc/core-win32-x64-msvc": "1.11.5"
+			},
+			"peerDependencies": {
+				"@swc/helpers": "*"
+			},
+			"peerDependenciesMeta": {
+				"@swc/helpers": {
+					"optional": true
+				}
+			}
+		},
+		"node_modules/@swc/core-darwin-arm64": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-darwin-arm64/-/core-darwin-arm64-1.11.5.tgz",
+			"integrity": "sha512-GEd1hzEx0mSGkJYMFMGLnrGgjL2rOsOsuYWyjyiA3WLmhD7o+n/EWBDo6mzD/9aeF8dzSPC0TnW216gJbvrNzA==",
+			"cpu": [
+				"arm64"
+			],
+			"license": "Apache-2.0 AND MIT",
+			"optional": true,
+			"os": [
+				"darwin"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/core-darwin-x64": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-darwin-x64/-/core-darwin-x64-1.11.5.tgz",
+			"integrity": "sha512-toz04z9wAClVvQSEY3xzrgyyeWBAfMWcKG4K0ugNvO56h/wczi2ZHRlnAXZW1tghKBk3z6MXqa/srfXgNhffKw==",
+			"cpu": [
+				"x64"
+			],
+			"license": "Apache-2.0 AND MIT",
+			"optional": true,
+			"os": [
+				"darwin"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/core-linux-arm-gnueabihf": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-linux-arm-gnueabihf/-/core-linux-arm-gnueabihf-1.11.5.tgz",
+			"integrity": "sha512-5SjmKxXdwbBpsYGTpgeXOXMIjS563/ntRGn8Zc12H/c4VfPrRLGhgbJ/48z2XVFyBLcw7BCHZyFuVX1+ZI3W0Q==",
+			"cpu": [
+				"arm"
+			],
+			"license": "Apache-2.0",
+			"optional": true,
+			"os": [
+				"linux"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/core-linux-arm64-gnu": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-linux-arm64-gnu/-/core-linux-arm64-gnu-1.11.5.tgz",
+			"integrity": "sha512-pydIlInHRzRIwB0NHblz3Dx58H/bsi0I5F2deLf9iOmwPNuOGcEEZF1Qatc7YIjP5DFbXK+Dcz+pMUZb2cc2MQ==",
+			"cpu": [
+				"arm64"
+			],
+			"license": "Apache-2.0 AND MIT",
+			"optional": true,
+			"os": [
+				"linux"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/core-linux-arm64-musl": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-linux-arm64-musl/-/core-linux-arm64-musl-1.11.5.tgz",
+			"integrity": "sha512-LhBHKjkZq5tJF1Lh0NJFpx7ROnCWLckrlIAIdSt9XfOV+zuEXJQOj+NFcM1eNk17GFfFyUMOZyGZxzYq5dveEQ==",
+			"cpu": [
+				"arm64"
+			],
+			"license": "Apache-2.0 AND MIT",
+			"optional": true,
+			"os": [
+				"linux"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/core-linux-x64-gnu": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-linux-x64-gnu/-/core-linux-x64-gnu-1.11.5.tgz",
+			"integrity": "sha512-dCi4xkxXlsk5sQYb3i413Cfh7+wMJeBYTvBZTD5xh+/DgRtIcIJLYJ2tNjWC4/C2i5fj+Ze9bKNSdd8weRWZ3A==",
+			"cpu": [
+				"x64"
+			],
+			"license": "Apache-2.0 AND MIT",
+			"optional": true,
+			"os": [
+				"linux"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/core-linux-x64-musl": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-linux-x64-musl/-/core-linux-x64-musl-1.11.5.tgz",
+			"integrity": "sha512-K0AC4TreM5Oo/tXNXnE/Gf5+5y/HwUdd7xvUjOpZddcX/RlsbYOKWLgOtA3fdFIuta7XC+vrGKmIhm5l70DSVQ==",
+			"cpu": [
+				"x64"
+			],
+			"license": "Apache-2.0 AND MIT",
+			"optional": true,
+			"os": [
+				"linux"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/core-win32-arm64-msvc": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-win32-arm64-msvc/-/core-win32-arm64-msvc-1.11.5.tgz",
+			"integrity": "sha512-wzum8sYUsvPY7kgUfuqVYTgIPYmBC8KPksoNM1fz5UfhudU0ciQuYvUBD47GIGOevaoxhLkjPH4CB95vh1mJ9w==",
+			"cpu": [
+				"arm64"
+			],
+			"license": "Apache-2.0 AND MIT",
+			"optional": true,
+			"os": [
+				"win32"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/core-win32-ia32-msvc": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-win32-ia32-msvc/-/core-win32-ia32-msvc-1.11.5.tgz",
+			"integrity": "sha512-lco7mw0TPRTpVPR6NwggJpjdUkAboGRkLrDHjIsUaR+Y5+0m5FMMkHOMxWXAbrBS5c4ph7QErp4Lma4r9Mn5og==",
+			"cpu": [
+				"ia32"
+			],
+			"license": "Apache-2.0 AND MIT",
+			"optional": true,
+			"os": [
+				"win32"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/core-win32-x64-msvc": {
+			"version": "1.11.5",
+			"resolved": "https://registry.npmjs.org/@swc/core-win32-x64-msvc/-/core-win32-x64-msvc-1.11.5.tgz",
+			"integrity": "sha512-E+DApLSC6JRK8VkDa4bNsBdD7Qoomx1HvKVZpOXl9v94hUZI5GMExl4vU5isvb+hPWL7rZ0NeI7ITnVLgLJRbA==",
+			"cpu": [
+				"x64"
+			],
+			"license": "Apache-2.0 AND MIT",
+			"optional": true,
+			"os": [
+				"win32"
+			],
+			"engines": {
+				"node": ">=10"
+			}
+		},
+		"node_modules/@swc/counter": {
+			"version": "0.1.3",
+			"resolved": "https://registry.npmjs.org/@swc/counter/-/counter-0.1.3.tgz",
+			"integrity": "sha512-e2BR4lsJkkRlKZ/qCHPw9ZaSxc0MVUd7gtbtaB7aMvHeJVYe8sOB8DBZkP2DtISHGSku9sCK6T6cnY0CtXrOCQ==",
+			"license": "Apache-2.0"
+		},
+		"node_modules/@swc/types": {
+			"version": "0.1.19",
+			"resolved": "https://registry.npmjs.org/@swc/types/-/types-0.1.19.tgz",
+			"integrity": "sha512-WkAZaAfj44kh/UFdAQcrMP1I0nwRqpt27u+08LMBYMqmQfwwMofYoMh/48NGkMMRfC4ynpfwRbJuu8ErfNloeA==",
+			"license": "Apache-2.0",
+			"dependencies": {
+				"@swc/counter": "^0.1.3"
+			}
+		},
 		"node_modules/@types/estree": {
 			"version": "1.0.6",
 			"resolved": "https://registry.npmjs.org/@types/estree/-/estree-1.0.6.tgz",
@@ -1120,12 +1333,6 @@
 				"node": ">= 0.4"
 			}
 		},
-		"node_modules/duplexer": {
-			"version": "0.1.2",
-			"resolved": "https://registry.npmjs.org/duplexer/-/duplexer-0.1.2.tgz",
-			"integrity": "sha512-jtD6YG370ZCIi/9GTaJKQxWTZD045+4R4hTk/x1UyoqadyJ9x9CgSi1RlVDQF8U2sxLLSnFkCaMihqljHIWgMg==",
-			"license": "MIT"
-		},
 		"node_modules/eastasianwidth": {
 			"version": "0.2.0",
 			"resolved": "https://registry.npmjs.org/eastasianwidth/-/eastasianwidth-0.2.0.tgz",
@@ -1649,21 +1856,6 @@
 			"integrity": "sha512-OP2IUU6HeYKJi3i0z4A19kHMQoLVs4Hc+DPqqxI2h/DPZHTm/vjsfC6P0b4jCMy14XizLBqvndQ+UilD7707Jw==",
 			"license": "MIT"
 		},
-		"node_modules/figures": {
-			"version": "3.2.0",
-			"resolved": "https://registry.npmjs.org/figures/-/figures-3.2.0.tgz",
-			"integrity": "sha512-yaduQFRKLXYOGgEn6AZau90j3ggSOyiqXU0F9JZfeXYhNa+Jk4X+s45A2zg5jns87GAFa34BBm2kXw4XpNcbdg==",
-			"license": "MIT",
-			"dependencies": {
-				"escape-string-regexp": "^1.0.5"
-			},
-			"engines": {
-				"node": ">=8"
-			},
-			"funding": {
-				"url": "https://github.com/sponsors/sindresorhus"
-			}
-		},
 		"node_modules/file-entry-cache": {
 			"version": "8.0.0",
 			"resolved": "https://registry.npmjs.org/file-entry-cache/-/file-entry-cache-8.0.0.tgz",
@@ -2239,82 +2431,6 @@
 				"node": ">=8"
 			}
 		},
-		"node_modules/grunt-contrib-uglify": {
-			"version": "5.2.2",
-			"resolved": "https://registry.npmjs.org/grunt-contrib-uglify/-/grunt-contrib-uglify-5.2.2.tgz",
-			"integrity": "sha512-ITxiWxrjjP+RZu/aJ5GLvdele+sxlznh+6fK9Qckio5ma8f7Iv8woZjRkGfafvpuygxNefOJNc+hfjjBayRn2Q==",
-			"license": "MIT",
-			"dependencies": {
-				"chalk": "^4.1.2",
-				"maxmin": "^3.0.0",
-				"uglify-js": "^3.16.1",
-				"uri-path": "^1.0.0"
-			},
-			"engines": {
-				"node": ">=12"
-			}
-		},
-		"node_modules/grunt-contrib-uglify/node_modules/ansi-styles": {
-			"version": "4.3.0",
-			"resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-4.3.0.tgz",
-			"integrity": "sha512-zbB9rCJAT1rbjiVDb2hqKFHNYLxgtk8NURxZ3IZwD3F6NtxbXZQCnnSi1Lkx+IDohdPlFp222wVALIheZJQSEg==",
-			"license": "MIT",
-			"dependencies": {
-				"color-convert": "^2.0.1"
-			},
-			"engines": {
-				"node": ">=8"
-			},
-			"funding": {
-				"url": "https://github.com/chalk/ansi-styles?sponsor=1"
-			}
-		},
-		"node_modules/grunt-contrib-uglify/node_modules/chalk": {
-			"version": "4.1.2",
-			"resolved": "https://registry.npmjs.org/chalk/-/chalk-4.1.2.tgz",
-			"integrity": "sha512-oKnbhFyRIXpUuez8iBMmyEa4nbj4IOQyuhc/wy9kY7/WVPcwIO9VA668Pu8RkO7+0G76SLROeyw9CpQ061i4mA==",
-			"license": "MIT",
-			"dependencies": {
-				"ansi-styles": "^4.1.0",
-				"supports-color": "^7.1.0"
-			},
-			"engines": {
-				"node": ">=10"
-			},
-			"funding": {
-				"url": "https://github.com/chalk/chalk?sponsor=1"
-			}
-		},
-		"node_modules/grunt-contrib-uglify/node_modules/color-convert": {
-			"version": "2.0.1",
-			"resolved": "https://registry.npmjs.org/color-convert/-/color-convert-2.0.1.tgz",
-			"integrity": "sha512-RRECPsj7iu/xb5oKYcsFHSppFNnsj/52OVTRKb4zP5onXwVF3zVmmToNcOfGC+CRDpfK/U584fMg38ZHCaElKQ==",
-			"license": "MIT",
-			"dependencies": {
-				"color-name": "~1.1.4"
-			},
-			"engines": {
-				"node": ">=7.0.0"
-			}
-		},
-		"node_modules/grunt-contrib-uglify/node_modules/color-name": {
-			"version": "1.1.4",
-			"resolved": "https://registry.npmjs.org/color-name/-/color-name-1.1.4.tgz",
-			"integrity": "sha512-dOy+3AuW3a2wNbZHIuMZpTcgjGuLU/uBL/ubcZF9OXbDo8ff4O8yVp5Bf0efS8uEoYo5q4Fx7dY9OgQGXgAsQA==",
-			"license": "MIT"
-		},
-		"node_modules/grunt-contrib-uglify/node_modules/supports-color": {
-			"version": "7.2.0",
-			"resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.2.0.tgz",
-			"integrity": "sha512-qpCAvRl9stuOHveKsn7HncJRvv501qIacKzQlO/+Lwxc9+0q2wLyv4Dfvt80/DPn2pqOBsJdDiogXGR9+OvwRw==",
-			"license": "MIT",
-			"dependencies": {
-				"has-flag": "^4.0.0"
-			},
-			"engines": {
-				"node": ">=8"
-			}
-		},
 		"node_modules/grunt-eslint": {
 			"version": "25.0.0",
 			"resolved": "https://registry.npmjs.org/grunt-eslint/-/grunt-eslint-25.0.0.tgz",
@@ -2556,19 +2672,6 @@
 				"node": "*"
 			}
 		},
-		"node_modules/gzip-size": {
-			"version": "5.1.1",
-			"resolved": "https://registry.npmjs.org/gzip-size/-/gzip-size-5.1.1.tgz",
-			"integrity": "sha512-FNHi6mmoHvs1mxZAds4PpdCS6QG8B4C1krxJsMutgxl5t3+GlRTzzI3NEkifXx2pVsOvJdOGSmIgDhQ55FwdPA==",
-			"license": "MIT",
-			"dependencies": {
-				"duplexer": "^0.1.1",
-				"pify": "^4.0.1"
-			},
-			"engines": {
-				"node": ">=6"
-			}
-		},
 		"node_modules/handlebars": {
 			"version": "4.7.8",
 			"resolved": "https://registry.npmjs.org/handlebars/-/handlebars-4.7.8.tgz",
@@ -3189,85 +3292,6 @@
 				"node": ">= 0.4"
 			}
 		},
-		"node_modules/maxmin": {
-			"version": "3.0.0",
-			"resolved": "https://registry.npmjs.org/maxmin/-/maxmin-3.0.0.tgz",
-			"integrity": "sha512-wcahMInmGtg/7c6a75fr21Ch/Ks1Tb+Jtoan5Ft4bAI0ZvJqyOw8kkM7e7p8hDSzY805vmxwHT50KcjGwKyJ0g==",
-			"license": "MIT",
-			"dependencies": {
-				"chalk": "^4.1.0",
-				"figures": "^3.2.0",
-				"gzip-size": "^5.1.1",
-				"pretty-bytes": "^5.3.0"
-			},
-			"engines": {
-				"node": ">=10"
-			},
-			"funding": {
-				"url": "https://github.com/sponsors/sindresorhus"
-			}
-		},
-		"node_modules/maxmin/node_modules/ansi-styles": {
-			"version": "4.3.0",
-			"resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-4.3.0.tgz",
-			"integrity": "sha512-zbB9rCJAT1rbjiVDb2hqKFHNYLxgtk8NURxZ3IZwD3F6NtxbXZQCnnSi1Lkx+IDohdPlFp222wVALIheZJQSEg==",
-			"license": "MIT",
-			"dependencies": {
-				"color-convert": "^2.0.1"
-			},
-			"engines": {
-				"node": ">=8"
-			},
-			"funding": {
-				"url": "https://github.com/chalk/ansi-styles?sponsor=1"
-			}
-		},
-		"node_modules/maxmin/node_modules/chalk": {
-			"version": "4.1.2",
-			"resolved": "https://registry.npmjs.org/chalk/-/chalk-4.1.2.tgz",
-			"integrity": "sha512-oKnbhFyRIXpUuez8iBMmyEa4nbj4IOQyuhc/wy9kY7/WVPcwIO9VA668Pu8RkO7+0G76SLROeyw9CpQ061i4mA==",
-			"license": "MIT",
-			"dependencies": {
-				"ansi-styles": "^4.1.0",
-				"supports-color": "^7.1.0"
-			},
-			"engines": {
-				"node": ">=10"
-			},
-			"funding": {
-				"url": "https://github.com/chalk/chalk?sponsor=1"
-			}
-		},
-		"node_modules/maxmin/node_modules/color-convert": {
-			"version": "2.0.1",
-			"resolved": "https://registry.npmjs.org/color-convert/-/color-convert-2.0.1.tgz",
-			"integrity": "sha512-RRECPsj7iu/xb5oKYcsFHSppFNnsj/52OVTRKb4zP5onXwVF3zVmmToNcOfGC+CRDpfK/U584fMg38ZHCaElKQ==",
-			"license": "MIT",
-			"dependencies": {
-				"color-name": "~1.1.4"
-			},
-			"engines": {
-				"node": ">=7.0.0"
-			}
-		},
-		"node_modules/maxmin/node_modules/color-name": {
-			"version": "1.1.4",
-			"resolved": "https://registry.npmjs.org/color-name/-/color-name-1.1.4.tgz",
-			"integrity": "sha512-dOy+3AuW3a2wNbZHIuMZpTcgjGuLU/uBL/ubcZF9OXbDo8ff4O8yVp5Bf0efS8uEoYo5q4Fx7dY9OgQGXgAsQA==",
-			"license": "MIT"
-		},
-		"node_modules/maxmin/node_modules/supports-color": {
-			"version": "7.2.0",
-			"resolved": "https://registry.npmjs.org/supports-color/-/supports-color-7.2.0.tgz",
-			"integrity": "sha512-qpCAvRl9stuOHveKsn7HncJRvv501qIacKzQlO/+Lwxc9+0q2wLyv4Dfvt80/DPn2pqOBsJdDiogXGR9+OvwRw==",
-			"license": "MIT",
-			"dependencies": {
-				"has-flag": "^4.0.0"
-			},
-			"engines": {
-				"node": ">=8"
-			}
-		},
 		"node_modules/media-typer": {
 			"version": "0.3.0",
 			"resolved": "https://registry.npmjs.org/media-typer/-/media-typer-0.3.0.tgz",
@@ -3770,15 +3794,6 @@
 				"url": "https://github.com/sponsors/jonschlinkert"
 			}
 		},
-		"node_modules/pify": {
-			"version": "4.0.1",
-			"resolved": "https://registry.npmjs.org/pify/-/pify-4.0.1.tgz",
-			"integrity": "sha512-uB80kBFb/tfd68bVleG9T5GGsGPjJrLAUpR5PZIrhBnIaRTQRjqdJSsIKkOP6OAIFbj7GOrcudc5pNjZ+geV2g==",
-			"license": "MIT",
-			"engines": {
-				"node": ">=6"
-			}
-		},
 		"node_modules/prelude-ls": {
 			"version": "1.2.1",
 			"resolved": "https://registry.npmjs.org/prelude-ls/-/prelude-ls-1.2.1.tgz",
@@ -3788,18 +3803,6 @@
 				"node": ">= 0.8.0"
 			}
 		},
-		"node_modules/pretty-bytes": {
-			"version": "5.6.0",
-			"resolved": "https://registry.npmjs.org/pretty-bytes/-/pretty-bytes-5.6.0.tgz",
-			"integrity": "sha512-FFw039TmrBqFK8ma/7OL3sDz/VytdtJr044/QUJtH0wK9lb9jLq9tJyIxUwtQJHwar2BqtiA4iCWSwo9JLkzFg==",
-			"license": "MIT",
-			"engines": {
-				"node": ">=6"
-			},
-			"funding": {
-				"url": "https://github.com/sponsors/sindresorhus"
-			}
-		},
 		"node_modules/process": {
 			"version": "0.11.10",
 			"resolved": "https://registry.npmjs.org/process/-/process-0.11.10.tgz",
@@ -4647,6 +4650,7 @@
 			"resolved": "https://registry.npmjs.org/uglify-js/-/uglify-js-3.19.3.tgz",
 			"integrity": "sha512-v3Xu+yuwBXisp6QYTcH4UbH+xYJXqnq2m/LtQVWKWzYc1iehYnLixoQDN9FH6/j9/oybfd6W9Ghwkl8+UMKTKQ==",
 			"license": "BSD-2-Clause",
+			"optional": true,
 			"bin": {
 				"uglifyjs": "bin/uglifyjs"
 			},
@@ -4700,15 +4704,6 @@
 				"punycode": "^2.1.0"
 			}
 		},
-		"node_modules/uri-path": {
-			"version": "1.0.0",
-			"resolved": "https://registry.npmjs.org/uri-path/-/uri-path-1.0.0.tgz",
-			"integrity": "sha512-8pMuAn4KacYdGMkFaoQARicp4HSw24/DHOVKWqVRJ8LhhAwPPFpdGvdL9184JVmUwe7vz7Z9n6IqI6t5n2ELdg==",
-			"license": "WTFPL OR MIT",
-			"engines": {
-				"node": ">= 0.10"
-			}
-		},
 		"node_modules/util-deprecate": {
 			"version": "1.0.2",
 			"resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
diff --git a/package.json b/package.json
index 7d5ed74..af8403a 100644
--- a/package.json
+++ b/package.json
@@ -8,9 +8,11 @@
 	},
 	"license": "MIT",
 	"dependencies": {
+		"@swc/core": "1.11.5",
 		"async": "3.2.6",
 		"builder-amd": "0.0.3",
 		"builder-jquery-css": "0.0.4",
+		"eslint": "9.21.0",
 		"eslint-config-jquery": "3.0.2",
 		"express": "^4.21.2",
 		"fast-glob": "^3.3.3",
@@ -22,7 +24,6 @@
 		"grunt-contrib-clean": "2.0.1",
 		"grunt-contrib-copy": "1.0.0",
 		"grunt-contrib-handlebars": "3.0.0",
-		"grunt-contrib-uglify": "5.2.2",
 		"grunt-eslint": "25.0.0",
 		"handlebars": "4.7.8",
 		"lzma": "2.3.2",
@@ -30,7 +31,6 @@
 		"qunit": "^2.24.1",
 		"semver": "^7.7.1",
 		"sqwish": "0.2.2",
-		"uglify-js": "3.19.3",
 		"winston": "^3.17.0",
 		"wolfy87-eventemitter": "5.2.9"
 	},
diff --git a/test/package.js b/test/package.js
index f913663..5e4c81d 100644
--- a/test/package.js
+++ b/test/package.js
@@ -2,19 +2,67 @@
 
 QUnit.module( "package" );
 
-let commonFiles, COMMON_FILES_TESTCASES, defaultTheme, someWidgets1, someWidgets2, themeFiles, THEME_FILES_TESTCASES;
+let defaultTheme, someWidgets1, someWidgets2,
+	commonFiles, COMMON_FILES_TESTCASES,
+	themeFiles, THEME_FILES_TESTCASES,
+	es5Files, ES5_FILES_TESTCASES;
 const JqueryUi = require( "../lib/jquery-ui" );
 const Package = require( "../lib/package" );
 const Packager = require( "node-packager" );
 const themeGallery = require( "../lib/themeroller-themegallery" )();
-
-function filePresent( files, filepath ) {
-	const filepathRe = filepath instanceof RegExp ? filepath : new RegExp( filepath.replace( /\*/g, "[^\/]*" ).replace( /\./g, "\\." ).replace( /(.*)/, "^$1$" ) );
-	return Object.keys( files ).some( function( filepath ) {
+const { ESLint } = require( "eslint" );
+
+function findFilepath( files, filepath ) {
+	const filepathRe = filepath instanceof RegExp ?
+		filepath :
+		new RegExp(
+			filepath
+				.replace( /\*/g, "[^\/]*" )
+				.replace( /\./g, "\\." )
+				.replace( /(.*)/, "^$1$" )
+		);
+	return Object.keys( files ).find( function( filepath ) {
 		return filepathRe.test( filepath );
 	} );
 }
 
+// An ESLint instance meant just to test if provided files are in ES5.
+// Use via the `ensureEs5` function.
+const eslintEs5 = new ESLint( {
+
+	// Disable searching for config files
+	overrideConfigFile: true,
+
+	overrideConfig: {
+
+		// Match all files. We will run it only on code we want anyway.
+		files: [ "*" ],
+
+		languageOptions: {
+			ecmaVersion: 5,
+			sourceType: "script"
+		},
+
+		linterOptions: {
+			noInlineConfig: true,
+			reportUnusedDisableDirectives: "off",
+			reportUnusedInlineConfigs: "off"
+		}
+	}
+} );
+
+async function ensureEs5( contents ) {
+	const results = await eslintEs5.lintText( contents );
+	if ( results[ 0 ].errorCount === 0 ) {
+		return { success: true };
+	}
+
+	return {
+		success: false,
+		message: results[ 0 ].messages.map( msgData => msgData.message ).join( "\n" )
+	};
+}
+
 defaultTheme = themeGallery[ 0 ].vars;
 someWidgets1 = "widget position widgets/autocomplete widgets/button widgets/menu widgets/progressbar widgets/spinner widgets/tabs".split( " " );
 someWidgets2 = "widget widgets/mouse position widgets/draggable widgets/resizable widgets/button widgets/datepicker widgets/dialog widgets/slider widgets/tooltip".split( " " );
@@ -32,10 +80,26 @@ commonFiles = [
 COMMON_FILES_TESTCASES = commonFiles.length;
 function commonFilesCheck( assert, files ) {
 	commonFiles.forEach( function( filepath ) {
-		assert.ok( filePresent( files, filepath ), "A common file \"" + filepath + "\" present." );
+		assert.ok( !!findFilepath( files, filepath ), "A common file \"" + filepath + "\" present." );
 	} );
 }
 
+es5Files = [
+	"jquery-ui.js",
+	"jquery-ui.min.js"
+];
+ES5_FILES_TESTCASES = es5Files.length * 2;
+async function es5FilesCheck( assert, files ) {
+	for ( const filepathPattern of es5Files ) {
+		const filepath = findFilepath( files, filepathPattern );
+		assert.ok( !!filepath, "A JS file \"" + filepath + "\" present." );
+		const lintResult = await ensureEs5( files[ filepath ] );
+		assert.ok( lintResult.success, `JS file "${ filepath }" needs to be in ES5 format.${
+			lintResult.success ? "" : `Messages from ESLint:\n${ lintResult.message }`
+		}` );
+	}
+}
+
 themeFiles = [
 	"jquery-ui.theme.css",
 	"jquery-ui.theme.min.css",
@@ -45,9 +109,9 @@ THEME_FILES_TESTCASES = themeFiles.length;
 function themeFilesCheck( assert, files, theme ) {
 	themeFiles.forEach( function( filepath ) {
 		if ( theme ) {
-			assert.ok( filePresent( files, filepath ), "A theme file \"" + filepath + "\" present." );
+			assert.ok( !!findFilepath( files, filepath ), "A theme file \"" + filepath + "\" present." );
 		} else {
-			assert.ok( !filePresent( files, filepath ), "The theme file \"" + filepath + "\" not included." );
+			assert.ok( !findFilepath( files, filepath ), "The theme file \"" + filepath + "\" not included." );
 		}
 	} );
 }
@@ -55,18 +119,20 @@ function themeFilesCheck( assert, files, theme ) {
 function runTests( context, jQueryUiVersion ) {
 
 	QUnit.test( `[${ jQueryUiVersion }]: select all components with the default theme`, function( assert ) {
-		assert.expect( COMMON_FILES_TESTCASES + THEME_FILES_TESTCASES );
+		assert.expect( COMMON_FILES_TESTCASES + ES5_FILES_TESTCASES + THEME_FILES_TESTCASES );
 
 		return new Promise( ( resolve, reject ) => {
 			const pkg = new Packager( context.files, Package, {
 				components: context.allComponents,
 				themeVars: defaultTheme
 			} );
-			pkg.toJson( function( error, files ) {
+			pkg.toJson( async function( error, files ) {
+				debugger;
 				if ( error ) {
 					return reject( error );
 				}
 				commonFilesCheck( assert, files );
+				await es5FilesCheck( assert, files );
 				themeFilesCheck( assert, files, true );
 				resolve();
 			} );
@@ -74,18 +140,19 @@ function runTests( context, jQueryUiVersion ) {
 	} );
 
 	QUnit.test( `[${ jQueryUiVersion }]: select all components with a different theme`, function( assert ) {
-		assert.expect( COMMON_FILES_TESTCASES + THEME_FILES_TESTCASES );
+		assert.expect( COMMON_FILES_TESTCASES + ES5_FILES_TESTCASES + THEME_FILES_TESTCASES );
 
 		return new Promise( ( resolve, reject ) => {
 			const pkg = new Packager( context.files, Package, {
 				components: context.allComponents,
 				themeVars: themeGallery[ 1 ].vars
 			} );
-			pkg.toJson( function( error, files ) {
+			pkg.toJson( async function( error, files ) {
 				if ( error ) {
 					return reject( error );
 				}
 				commonFilesCheck( assert, files );
+				await es5FilesCheck( assert, files );
 				themeFilesCheck( assert, files, true );
 				resolve();
 			} );
@@ -93,7 +160,7 @@ function runTests( context, jQueryUiVersion ) {
 	} );
 
 	QUnit.test( `[${ jQueryUiVersion }]: test: select all widgets`, function( assert ) {
-		assert.expect( COMMON_FILES_TESTCASES + THEME_FILES_TESTCASES + 2 );
+		assert.expect( COMMON_FILES_TESTCASES + ES5_FILES_TESTCASES + THEME_FILES_TESTCASES + 2 );
 
 		return new Promise( ( resolve, reject ) => {
 			const allWidgets = context.allWidgets;
@@ -102,11 +169,12 @@ function runTests( context, jQueryUiVersion ) {
 				themeVars: defaultTheme
 			} );
 			assert.strictEqual( allWidgets.length, 15, "All widgets count" );
-			pkg.toJson( function( error, files ) {
+			pkg.toJson( async function( error, files ) {
 				if ( error ) {
 					return reject( error );
 				}
 				commonFilesCheck( assert, files );
+				await es5FilesCheck( assert, files );
 				themeFilesCheck( assert, files, true );
 
 				// 15 widgets, 14 have CSS, plus core, theme, draggable, resizable
@@ -119,7 +187,7 @@ function runTests( context, jQueryUiVersion ) {
 	} );
 
 	QUnit.test( `[${ jQueryUiVersion }]: test: select all effects`, function( assert ) {
-		assert.expect( COMMON_FILES_TESTCASES + THEME_FILES_TESTCASES + 1 );
+		assert.expect( COMMON_FILES_TESTCASES + ES5_FILES_TESTCASES + THEME_FILES_TESTCASES + 1 );
 
 		return new Promise( ( resolve, reject ) => {
 			const pkg = new Packager( context.files, Package, {
@@ -127,11 +195,12 @@ function runTests( context, jQueryUiVersion ) {
 				themeVars: null
 			} );
 			assert.strictEqual( context.allEffects.length, 16, "All effects count" );
-			pkg.toJson( function( error, files ) {
+			pkg.toJson( async function( error, files ) {
 				if ( error ) {
 					return reject( error );
 				}
 				commonFilesCheck( assert, files );
+				await es5FilesCheck( assert, files );
 				themeFilesCheck( assert, files, false );
 				resolve();
 			} );
@@ -139,7 +208,7 @@ function runTests( context, jQueryUiVersion ) {
 	} );
 
 	QUnit.test( `[${ jQueryUiVersion }]: select some widgets (1)`, function( assert ) {
-		assert.expect( COMMON_FILES_TESTCASES + THEME_FILES_TESTCASES + 2 );
+		assert.expect( COMMON_FILES_TESTCASES + ES5_FILES_TESTCASES + THEME_FILES_TESTCASES + 2 );
 
 		return new Promise( ( resolve, reject ) => {
 			const pkg = new Packager( context.files, Package, {
@@ -147,11 +216,12 @@ function runTests( context, jQueryUiVersion ) {
 				themeVars: defaultTheme
 			} );
 			assert.strictEqual( someWidgets1.length, 8, "Some widgets count" );
-			pkg.toJson( function( error, files ) {
+			pkg.toJson( async function( error, files ) {
 				if ( error ) {
 					return reject( error );
 				}
 				commonFilesCheck( assert, files );
+				await es5FilesCheck( assert, files );
 				themeFilesCheck( assert, files, true );
 
 				// 8 components selected, 6 have CSS, plus core, theme,
@@ -165,7 +235,7 @@ function runTests( context, jQueryUiVersion ) {
 	} );
 
 	QUnit.test( `[${ jQueryUiVersion }]: select some widgets (2)`, function( assert ) {
-		assert.expect( COMMON_FILES_TESTCASES + THEME_FILES_TESTCASES + 2 );
+		assert.expect( COMMON_FILES_TESTCASES + ES5_FILES_TESTCASES + THEME_FILES_TESTCASES + 2 );
 
 		return new Promise( ( resolve, reject ) => {
 			const pkg = new Packager( context.files, Package, {
@@ -173,11 +243,12 @@ function runTests( context, jQueryUiVersion ) {
 				themeVars: defaultTheme
 			} );
 			assert.strictEqual( someWidgets2.length, 10, "Some widgets count" );
-			pkg.toJson( function( error, files ) {
+			pkg.toJson( async function( error, files ) {
 				if ( error ) {
 					return reject( error );
 				}
 				commonFilesCheck( assert, files );
+				await es5FilesCheck( assert, files );
 				themeFilesCheck( assert, files, true );
 
 				// 10 components selected, 7 have CSS, plus core, theme,