diff --git a/index.js b/index.js
index 0344c367..3af837b8 100644
--- a/index.js
+++ b/index.js
@@ -13,6 +13,14 @@
  * @import webpack from 'webpack'
  */
 
+/**
+ * @import { OptionsCallback } from './lib/utils/apply-options-callback.js'
+ */
+
+/**
+ * @typedef {{from: string, pattern?: RegExp|string, to?: string|null, includeSubdirectories?: boolean, context?: string}} CopyFilesOptions
+ */
+
 const EncoreProxy = require('./lib/EncoreProxy');
 const WebpackConfig = require('./lib/WebpackConfig');
 const configGenerator = require('./lib/config-generator');
@@ -117,7 +125,7 @@ class Encore {
      * })
      * ```
      *
-     * @param {Function} definePluginOptionsCallback
+     * @param {OptionsCallback<ConstructorParameters<typeof webpack.DefinePlugin>[0]>} definePluginOptionsCallback
      * @returns {Encore}
      */
     configureDefinePlugin(definePluginOptionsCallback = () => {}) {
@@ -138,7 +146,7 @@ class Encore {
      * })
      * ```
      *
-     * @param {Function} friendlyErrorsPluginOptionsCallback
+     * @param {OptionsCallback<object>} friendlyErrorsPluginOptionsCallback
      * @returns {Encore}
      */
     configureFriendlyErrorsPlugin(friendlyErrorsPluginOptionsCallback = () => {}) {
@@ -159,7 +167,7 @@ class Encore {
      * })
      * ```
      *
-     * @param {Function} manifestPluginOptionsCallback
+     * @param {OptionsCallback<object>} manifestPluginOptionsCallback
      * @returns {Encore}
      */
     configureManifestPlugin(manifestPluginOptionsCallback = () => {}) {
@@ -185,7 +193,7 @@ class Encore {
      * })
      * ```
      *
-     * @param {Function} terserPluginOptionsCallback
+     * @param {OptionsCallback<import('terser-webpack-plugin').BasePluginOptions & import('terser-webpack-plugin').DefinedDefaultMinimizerAndOptions<import('terser').MinifyOptions>>} terserPluginOptionsCallback
      * @returns {Encore}
      */
     configureTerserPlugin(terserPluginOptionsCallback = () => {}) {
@@ -206,7 +214,7 @@ class Encore {
      * })
      * ```
      *
-     * @param {Function} cssMinimizerPluginOptionsCallback
+     * @param {OptionsCallback<import('css-minimizer-webpack-plugin').BasePluginOptions & import('css-minimizer-webpack-plugin').DefinedDefaultMinimizerAndOptions<import('css-minimizer-webpack-plugin').CssNanoOptionsExtended>>} cssMinimizerPluginOptionsCallback
      * @returns {Encore}
      */
     configureCssMinimizerPlugin(cssMinimizerPluginOptionsCallback = () => {}) {
@@ -226,10 +234,10 @@ class Encore {
      * If the JavaScript file imports/requires CSS/Sass/LESS files,
      * then a CSS file (e.g. main.css) will also be output.
      *
-     * @param {string} name       The name (without extension) that will be used
-     *                            as the output filename (e.g. app will become app.js)
-     *                            in the output directory.
-     * @param {string|Array} src  The path to the source file (or files)
+     * @param {string} name          The name (without extension) that will be used
+     *                               as the output filename (e.g. app will become app.js)
+     *                               in the output directory.
+     * @param {string|string[]} src  The path to the source file (or files)
      * @returns {Encore}
      */
     addEntry(name, src) {
@@ -252,7 +260,7 @@ class Encore {
      * If the JavaScript files imports/requires CSS/Sass/LESS files,
      * then a CSS file (e.g. main.css) will also be output.
      *
-     * @param {Record<string, string|Array>} entries where the Keys are the
+     * @param {Record<string, string|string[]>} entries where the Keys are the
      *                            names (without extension) that will be used
      *                            as the output filename (e.g. app will become app.js)
      *                            in the output directory. The values are the path(s)
@@ -278,10 +286,10 @@ class Encore {
      * is to use addEntry() and then require/import your CSS files from
      * within your JavaScript files.
      *
-     * @param {string} name       The name (without extension) that will be used
-     *                            as the output filename (e.g. app will become app.css)
-     *                            in the output directory.
-     * @param {string|Array} src  The path to the source file (or files)
+     * @param {string} name          The name (without extension) that will be used
+     *                               as the output filename (e.g. app will become app.css)
+     *                               in the output directory.
+     * @param {string|string[]} src  The path to the source file (or files)
      * @returns {Encore}
      */
     addStyleEntry(name, src) {
@@ -326,7 +334,7 @@ class Encore {
      * Encore.addPlugin(new MyWebpackPlugin(), PluginPriorities.DefinePlugin);
      * ```
      *
-     * @param {object} plugin
+     * @param {webpack.WebpackPluginInstance} plugin
      * @param {number} priority
      * @returns {Encore}
      */
@@ -339,7 +347,7 @@ class Encore {
     /**
      * Adds a custom loader config
      *
-     * @param {object} loader The loader config object
+     * @param {webpack.RuleSetRule} loader The loader config object
      * @returns {Encore}
      */
     addLoader(loader) {
@@ -351,7 +359,7 @@ class Encore {
     /**
      * Alias to addLoader
      *
-     * @param {object} rule
+     * @param {webpack.RuleSetRule} rule
      * @returns {Encore}
      */
     addRule(rule) {
@@ -414,7 +422,7 @@ class Encore {
      * ]);
      * ```
      *
-     * @param {*} externals
+     * @param {webpack.Externals} externals
      * @returns {Encore}
      */
     addExternals(externals) {
@@ -584,7 +592,7 @@ class Encore {
      *      - {string} context (default: path of the source directory)
      *              The context to use as a root path when copying files.
      *
-     * @param {object|Array} configs
+     * @param {CopyFilesOptions|CopyFilesOptions[]} configs
      * @returns {Encore}
      */
     copyFiles(configs) {
@@ -669,7 +677,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} callback
+     * @param {OptionsCallback<object>} callback
      * @returns {Encore}
      */
     configureSplitChunks(callback) {
@@ -691,7 +699,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} callback
+     * @param {OptionsCallback<Exclude<webpack.Configuration['watchOptions'], undefined>>} callback
      * @returns {Encore}
      */
     configureWatchOptions(callback) {
@@ -718,7 +726,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} callback
+     * @param {OptionsCallback<import('webpack-dev-server').Configuration>} callback
      * @returns {Encore}
      */
     configureDevServerOptions(callback) {
@@ -794,7 +802,7 @@ class Encore {
      * })
      * ```
      *
-     * @param {Function} postCssLoaderOptionsCallback
+     * @param {OptionsCallback<object>} postCssLoaderOptionsCallback
      * @returns {Encore}
      */
     enablePostCssLoader(postCssLoaderOptionsCallback = () => {}) {
@@ -834,8 +842,8 @@ class Encore {
      *              Options parameters for resolve-url-loader
      *              // https://www.npmjs.com/package/resolve-url-loader#options
      *
-     * @param {Function} sassLoaderOptionsCallback
-     * @param {object} encoreOptions
+     * @param {OptionsCallback<object>} sassLoaderOptionsCallback
+     * @param {{resolveUrlLoader?: boolean, resolveUrlLoaderOptions?: object}} encoreOptions
      * @returns {Encore}
      */
     enableSassLoader(sassLoaderOptionsCallback = () => {}, encoreOptions = {}) {
@@ -861,7 +869,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} lessLoaderOptionsCallback
+     * @param {OptionsCallback<object>} lessLoaderOptionsCallback
      * @returns {Encore}
      */
     enableLessLoader(lessLoaderOptionsCallback = () => {}) {
@@ -886,7 +894,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} stylusLoaderOptionsCallback
+     * @param {OptionsCallback<object>} stylusLoaderOptionsCallback
      * @returns {Encore}
      */
     enableStylusLoader(stylusLoaderOptionsCallback = () => {}) {
@@ -931,7 +939,7 @@ class Encore {
      * ```
      *
      * Supported options:
-     *      - {Condition} exclude (default=/(node_modules|bower_components)/)
+     *      - {webpack.RuleSetCondition} exclude (default=/(node_modules|bower_components)/)
      *              A Webpack Condition passed to the JS/JSX rule that
      *              determines which files and folders should not be
      *              processed by Babel (https://webpack.js.org/configuration/module/#condition).
@@ -966,8 +974,8 @@ class Encore {
      *              It should contain the version of core-js you added to your project
      *              if useBuiltIns isn't set to false.
      *
-     * @param {Function|null} callback
-     * @param {object} encoreOptions
+     * @param {OptionsCallback<object>|null} callback
+     * @param {{exclude?: webpack.RuleSetCondition, includeNodeModules?: string[], useBuiltIns?: 'usage' | 'entry' | false, corejs?: number|string|{ version: string, proposals: boolean }|null}} encoreOptions
      * @returns {Encore}
      */
     configureBabel(callback, encoreOptions = {}) {
@@ -992,7 +1000,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} callback
+     * @param {OptionsCallback<object>} callback
      * @returns {Encore}
      */
     configureBabelPresetEnv(callback) {
@@ -1013,7 +1021,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} callback
+     * @param {OptionsCallback<object>} callback
      * @returns {Encore}
      */
     configureCssLoader(callback) {
@@ -1055,8 +1063,8 @@ class Encore {
      * });
      * ```
      *
-     * @param {object} buildDependencies
-     * @param {Function} cacheCallback
+     * @param {Record<string, string[]>} buildDependencies
+     * @param {OptionsCallback<webpack.FileCacheOptions>} cacheCallback
      * @returns {Encore}
      */
     enableBuildCache(buildDependencies, cacheCallback = (cache) => {}) {
@@ -1083,8 +1091,8 @@ class Encore {
      * );
      * ```
      *
-     * @param {Function} loaderOptionsCallback
-     * @param {Function} pluginOptionsCallback
+     * @param {OptionsCallback<import('mini-css-extract-plugin').LoaderOptions>} loaderOptionsCallback
+     * @param {OptionsCallback<import('mini-css-extract-plugin').PluginOptions>} pluginOptionsCallback
      * @returns {Encore}
      */
     configureMiniCssExtractPlugin(loaderOptionsCallback, pluginOptionsCallback = () => {}) {
@@ -1121,7 +1129,7 @@ class Encore {
      * Encore.enablePreactPreset({ preactCompat: true })
      * ```
      *
-     * @param {object} options
+     * @param {{preactCompat?: boolean}} options
      * @returns {Encore}
      */
     enablePreactPreset(options = {}) {
@@ -1149,7 +1157,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} callback
+     * @param {OptionsCallback<object>} callback
      * @returns {Encore}
      */
     enableTypeScriptLoader(callback = () => {}) {
@@ -1164,7 +1172,7 @@ class Encore {
      *
      * This is a build optimization API to reduce build times.
      *
-     * @param {Function} forkedTypeScriptTypesCheckOptionsCallback
+     * @param {OptionsCallback<object>} forkedTypeScriptTypesCheckOptionsCallback
      * @returns {Encore}
      */
     enableForkedTypeScriptTypesChecking(forkedTypeScriptTypesCheckOptionsCallback = () => {}) {
@@ -1252,8 +1260,8 @@ class Encore {
      *              Configure Babel to use the preset "@vue/babel-preset-jsx",
      *              in order to enable JSX usage in Vue components.
      *
-     * @param {Function} vueLoaderOptionsCallback
-     * @param {object} encoreOptions
+     * @param {OptionsCallback<object>} vueLoaderOptionsCallback
+     * @param {{useJsx?: boolean, version?: number, runtimeCompilerBuild?: boolean}} encoreOptions
      * @returns {Encore}
      */
     enableVueLoader(vueLoaderOptionsCallback = () => {}, encoreOptions = {}) {
@@ -1279,7 +1287,7 @@ class Encore {
      * ```
      *
      * @param {boolean} enabled
-     * @param {Function} notifierPluginOptionsCallback
+     * @param {OptionsCallback<object>} notifierPluginOptionsCallback
      * @returns {Encore}
      */
     enableBuildNotifications(enabled = true, notifierPluginOptionsCallback = () => {}) {
@@ -1304,7 +1312,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} callback
+     * @param {OptionsCallback<object>} callback
      * @returns {Encore}
      */
     enableHandlebarsLoader(callback = () => {}) {
@@ -1351,7 +1359,7 @@ class Encore {
      * });
      * ```
      *
-     * @param {Function} callback
+     * @param {OptionsCallback<object>} callback
      * @returns {Encore}
      */
     configureStyleLoader(callback) {
@@ -1383,7 +1391,7 @@ class Encore {
      * which is overridden for both fonts and images. See configureImageRule()
      * and configureFontRule() to control those filenames.
      *
-     * @param {object} filenames
+     * @param {{js?: string, css?: string, images?: string, fonts?: string}} filenames
      * @returns {Encore}
      */
     configureFilenames(filenames) {
@@ -1437,8 +1445,8 @@ class Encore {
      * });
      * ```
      *
-     * @param {object} options
-     * @param {string|object|Function} ruleCallback
+     * @param {{filename?: string, maxSize?: number|null, type?: string, enabled?: boolean}} options
+     * @param {OptionsCallback<webpack.RuleSetRule>} ruleCallback
      * @returns {Encore}
      */
     configureImageRule(options = {}, ruleCallback = (rule) => {}) {
@@ -1454,8 +1462,8 @@ class Encore {
      *
      * See configureImageRule() for more details.
      *
-     * @param {object} options
-     * @param {string|object|Function} ruleCallback
+     * @param {{filename?: string, maxSize?: number|null, type?: string, enabled?: boolean}} options
+     * @param {OptionsCallback<webpack.RuleSetRule>} ruleCallback
      * @returns {Encore}
      */
     configureFontRule(options = {}, ruleCallback = (rule) => {}) {
@@ -1479,7 +1487,7 @@ class Encore {
      * ```
      *
      * @param {string} name
-     * @param {Function} callback
+     * @param {OptionsCallback<webpack.RuleSetRule>} callback
      * @returns {Encore}
      */
     configureLoaderRule(name, callback) {
@@ -1501,7 +1509,7 @@ class Encore {
      * })
      * ```
      *
-     * @param {Function} cleanOptionsCallback
+     * @param {OptionsCallback<Exclude<ConstructorParameters<typeof webpack.CleanPlugin>[0], undefined>>} cleanOptionsCallback
      * @returns {Encore}
      */
     cleanupOutputBeforeBuild(cleanOptionsCallback = () => {}) {
@@ -1539,7 +1547,7 @@ class Encore {
      * ```
      *
      * @param {boolean} enabled
-     * @param {string|Array} algorithms
+     * @param {string|string[]} algorithms
      * @returns {Encore}
      */
     enableIntegrityHashes(enabled = true, algorithms = ['sha384']) {
@@ -1647,7 +1655,7 @@ class Encore {
      * )
      * ```
      *
-     * Be aware than using this method will also reset the current
+     * Be aware that using this method will also reset the current
      * webpack configuration.
      *
      * @param {string} environment
@@ -1672,7 +1680,7 @@ class Encore {
 
     /**
      * Check if Encore was either called through
-     * the CLI utility or after being manually intialized
+     * the CLI utility or after being manually initialized
      * using Encore.configureRuntimeEnvironment.
      *
      * @returns {boolean}
@@ -1684,7 +1692,7 @@ class Encore {
     /**
      * Clear the runtime environment.
      *
-     * Be aware than using this method will also reset the
+     * Be aware that using this method will also reset the
      * current webpack configuration.
      *
      * @returns {void}
diff --git a/lib/WebpackConfig.js b/lib/WebpackConfig.js
index 63bf5f9c..f1bcd244 100644
--- a/lib/WebpackConfig.js
+++ b/lib/WebpackConfig.js
@@ -13,6 +13,18 @@
  * @import RuntimeConfig from './config/RuntimeConfig'
  */
 
+/**
+ * @import webpack from 'webpack'
+ */
+
+/**
+ * @import { OptionsCallback } from './utils/apply-options-callback.js'
+ */
+
+/**
+ * @import { CopyFilesOptions } from '../index.js'
+ */
+
 const path = require('path');
 const fs = require('fs');
 const crypto = require('crypto');
@@ -72,12 +84,14 @@ class WebpackConfig {
         this.cleanupOutput = false;
         this.usePersistentCache = false;
         this.extractCss = true;
+        /** @type {{filename: string, maxSize: number|null, type: string, enabled: boolean}} */
         this.imageRuleOptions = {
             type: 'asset/resource',
             maxSize: null,
             filename: 'images/[name].[hash:8][ext]',
             enabled: true,
         };
+        /** @type {{filename: string, maxSize: number|null, type: string, enabled: boolean}} */
         this.fontRuleOptions = {
             type: 'asset/resource',
             maxSize: null,
@@ -101,6 +115,9 @@ class WebpackConfig {
 
         // Features/Loaders options
         this.copyFilesConfigs = [];
+        /**
+         * @type {{resolveUrlLoader: boolean, resolveUrlLoaderOptions: object}}
+         */
         this.sassOptions = {
             resolveUrlLoader: true,
             resolveUrlLoaderOptions: {}
@@ -108,6 +125,7 @@ class WebpackConfig {
         this.preactOptions = {
             preactCompat: false
         };
+        /** @type {{exclude: webpack.RuleSetCondition, useBuiltIns: 'usage'|'entry'|false, corejs: number|string|{ version: string, proposals: boolean }|null}} */
         this.babelOptions = {
             exclude: /(node_modules|bower_components)/,
             useBuiltIns: false,
@@ -119,27 +137,47 @@ class WebpackConfig {
             version: null,
             runtimeCompilerBuild: null
         };
+        /** @type {Record<string, string[]>} */
         this.persistentCacheBuildDependencies = {};
 
         // Features/Loaders options callbacks
+        /** @type {OptionsCallback<webpack.RuleSetRule>} */
         this.imageRuleCallback = () => {};
+        /** @type {OptionsCallback<webpack.RuleSetRule>} */
         this.fontRuleCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.postCssLoaderOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.sassLoaderOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.lessLoaderOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.stylusLoaderOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.babelConfigurationCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.babelPresetEnvOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.cssLoaderConfigurationCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.styleLoaderConfigurationCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.splitChunksConfigurationCallback = () => {};
+        /** @type {OptionsCallback<Exclude<webpack.Configuration['watchOptions'], undefined>>} */
         this.watchOptionsConfigurationCallback = () => {};
+        /** @type {OptionsCallback<import('webpack-dev-server').Configuration>} */
         this.devServerOptionsConfigurationCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.vueLoaderOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.tsConfigurationCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.handlebarsConfigurationCallback = () => {};
+        /** @type {OptionsCallback<import('mini-css-extract-plugin').LoaderOptions>} */
         this.miniCssExtractLoaderConfigurationCallback = () => {};
+        /** @type {OptionsCallback<import('mini-css-extract-plugin').PluginOptions>} */
         this.miniCssExtractPluginConfigurationCallback = () => {};
+        /** @type {Record<string, OptionsCallback<webpack.RuleSetRule>>} */
         this.loaderConfigurationCallbacks = {
             javascript: () => {},
             css: () => {},
@@ -155,14 +193,23 @@ class WebpackConfig {
         };
 
         // Plugins callbacks
+        /** @type {OptionsCallback<Exclude<ConstructorParameters<typeof webpack.CleanPlugin>[0], undefined>>} */
         this.cleanOptionsCallback = () => {};
+        /** @type {OptionsCallback<ConstructorParameters<typeof webpack.DefinePlugin>[0]>} */
         this.definePluginOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.forkedTypeScriptTypesCheckOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.friendlyErrorsPluginOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.manifestPluginOptionsCallback = () => {};
+        /** @type {OptionsCallback<import('terser-webpack-plugin').BasePluginOptions & import('terser-webpack-plugin').DefinedDefaultMinimizerAndOptions<import('terser').MinifyOptions>>} */
         this.terserPluginOptionsCallback = () => {};
+        /** @type {OptionsCallback<import('css-minimizer-webpack-plugin').BasePluginOptions & import('css-minimizer-webpack-plugin').DefinedDefaultMinimizerAndOptions<import('css-minimizer-webpack-plugin').CssNanoOptionsExtended>>} */
         this.cssMinimizerPluginOptionsCallback = () => {};
+        /** @type {OptionsCallback<object>} */
         this.notifierPluginOptionsCallback = () => {};
+        /** @type {OptionsCallback<webpack.FileCacheOptions>} */
         this.persistentCacheCallback = () => {};
     }
 
@@ -242,6 +289,9 @@ class WebpackConfig {
         this.manifestKeyPrefix = manifestKeyPrefix;
     }
 
+    /**
+     * @param {OptionsCallback<ConstructorParameters<typeof webpack.DefinePlugin>[0]>} definePluginOptionsCallback
+     */
     configureDefinePlugin(definePluginOptionsCallback = () => {}) {
         if (typeof definePluginOptionsCallback !== 'function') {
             throw new Error('Argument 1 to configureDefinePlugin() must be a callback function');
@@ -250,6 +300,9 @@ class WebpackConfig {
         this.definePluginOptionsCallback = definePluginOptionsCallback;
     }
 
+    /**
+     * @param {OptionsCallback<object>} friendlyErrorsPluginOptionsCallback
+     */
     configureFriendlyErrorsPlugin(friendlyErrorsPluginOptionsCallback = () => {}) {
         if (typeof friendlyErrorsPluginOptionsCallback !== 'function') {
             throw new Error('Argument 1 to configureFriendlyErrorsPlugin() must be a callback function');
@@ -258,6 +311,9 @@ class WebpackConfig {
         this.friendlyErrorsPluginOptionsCallback = friendlyErrorsPluginOptionsCallback;
     }
 
+    /**
+     * @param {OptionsCallback<object>} manifestPluginOptionsCallback
+     */
     configureManifestPlugin(manifestPluginOptionsCallback = () => {}) {
         if (typeof manifestPluginOptionsCallback !== 'function') {
             throw new Error('Argument 1 to configureManifestPlugin() must be a callback function');
@@ -266,6 +322,9 @@ class WebpackConfig {
         this.manifestPluginOptionsCallback = manifestPluginOptionsCallback;
     }
 
+    /**
+     * @param {OptionsCallback<import('terser-webpack-plugin').BasePluginOptions & import('terser-webpack-plugin').DefinedDefaultMinimizerAndOptions<import('terser').MinifyOptions>>} terserPluginOptionsCallback
+     */
     configureTerserPlugin(terserPluginOptionsCallback = () => {}) {
         if (typeof terserPluginOptionsCallback !== 'function') {
             throw new Error('Argument 1 to configureTerserPlugin() must be a callback function');
@@ -274,6 +333,9 @@ class WebpackConfig {
         this.terserPluginOptionsCallback = terserPluginOptionsCallback;
     }
 
+    /**
+     * @param {OptionsCallback<import('css-minimizer-webpack-plugin').BasePluginOptions & import('css-minimizer-webpack-plugin').DefinedDefaultMinimizerAndOptions<import('css-minimizer-webpack-plugin').CssNanoOptionsExtended>>} cssMinimizerPluginOptionsCallback
+     */
     configureCssMinimizerPlugin(cssMinimizerPluginOptionsCallback = () => {}) {
         if (typeof cssMinimizerPluginOptionsCallback !== 'function') {
             throw new Error('Argument 1 to configureCssMinimizerPlugin() must be a callback function');
@@ -356,6 +418,9 @@ class WebpackConfig {
         Object.assign(this.aliases, aliases);
     }
 
+    /**
+     * @param {webpack.Externals} externals
+     */
     addExternals(externals = []) {
         if (!Array.isArray(externals)) {
             externals = [externals];
@@ -372,6 +437,10 @@ class WebpackConfig {
         this.useSourceMaps = enabled;
     }
 
+    /**
+     * @param {OptionsCallback<object>|null} callback
+     * @param {{exclude?: webpack.RuleSetCondition, includeNodeModules?: string[], useBuiltIns?: 'usage' | 'entry' | false, corejs?: number|string|{ version: string, proposals: boolean }|null}} options
+     */
     configureBabel(callback, options = {}) {
         if (callback) {
             if (typeof callback !== 'function') {
@@ -433,6 +502,9 @@ class WebpackConfig {
         }
     }
 
+    /**
+     * @param {OptionsCallback<object>} callback
+     */
     configureBabelPresetEnv(callback) {
         if (typeof callback !== 'function') {
             throw new Error('Argument 1 to configureBabelPresetEnv() must be a callback function.');
@@ -445,6 +517,9 @@ class WebpackConfig {
         this.babelPresetEnvOptionsCallback = callback;
     }
 
+    /**
+     * @param {OptionsCallback<object>} callback
+     */
     configureCssLoader(callback) {
         if (typeof callback !== 'function') {
             throw new Error('Argument 1 to configureCssLoader() must be a callback function.');
@@ -453,6 +528,9 @@ class WebpackConfig {
         this.cssLoaderConfigurationCallback = callback;
     }
 
+    /**
+     * @param {OptionsCallback<object>} callback
+     */
     configureStyleLoader(callback) {
         if (typeof callback !== 'function') {
             throw new Error('Argument 1 to configureStyleLoader() must be a callback function.');
@@ -461,6 +539,10 @@ class WebpackConfig {
         this.styleLoaderConfigurationCallback = callback;
     }
 
+    /**
+     * @param {OptionsCallback<import('mini-css-extract-plugin').LoaderOptions>} loaderOptionsCallback
+     * @param {OptionsCallback<import('mini-css-extract-plugin').PluginOptions>} pluginOptionsCallback
+     */
     configureMiniCssExtractPlugin(loaderOptionsCallback, pluginOptionsCallback = () => {}) {
         if (typeof loaderOptionsCallback !== 'function') {
             throw new Error('Argument 1 to configureMiniCssExtractPluginLoader() must be a callback function.');
@@ -486,6 +568,9 @@ class WebpackConfig {
         this.shouldSplitEntryChunks = true;
     }
 
+    /**
+     * @param {OptionsCallback<object>} callback
+     */
     configureSplitChunks(callback) {
         if (typeof callback !== 'function') {
             throw new Error('Argument 1 to configureSplitChunks() must be a callback function.');
@@ -494,6 +579,9 @@ class WebpackConfig {
         this.splitChunksConfigurationCallback = callback;
     }
 
+    /**
+     * @param {OptionsCallback<Exclude<webpack.Configuration['watchOptions'], undefined>>} callback
+     */
     configureWatchOptions(callback) {
         if (typeof callback !== 'function') {
             throw new Error('Argument 1 to configureWatchOptions() must be a callback function.');
@@ -502,6 +590,9 @@ class WebpackConfig {
         this.watchOptionsConfigurationCallback = callback;
     }
 
+    /**
+     * @param {OptionsCallback<import('webpack-dev-server').Configuration>} callback
+     */
     configureDevServerOptions(callback) {
         if (typeof callback !== 'function') {
             throw new Error('Argument 1 to configureDevServerOptions() must be a callback function.');
@@ -510,6 +601,10 @@ class WebpackConfig {
         this.devServerOptionsConfigurationCallback = callback;
     }
 
+    /**
+     * @param {string} name
+     * @param {object} options
+     */
     addCacheGroup(name, options) {
         if (typeof name !== 'string') {
             throw new Error('Argument 1 to addCacheGroup() must be a string.');
@@ -540,6 +635,9 @@ class WebpackConfig {
         this.cacheGroups[name] = options;
     }
 
+    /**
+     * @param {CopyFilesOptions|CopyFilesOptions[]} configs
+     */
     copyFiles(configs = []) {
         if (!Array.isArray(configs)) {
             configs = [configs];
@@ -588,6 +686,9 @@ class WebpackConfig {
         }
     }
 
+    /**
+     * @param {OptionsCallback<object>} postCssLoaderOptionsCallback
+     */
     enablePostCssLoader(postCssLoaderOptionsCallback = () => {}) {
         this.usePostCssLoader = true;
 
@@ -598,6 +699,10 @@ class WebpackConfig {
         this.postCssLoaderOptionsCallback = postCssLoaderOptionsCallback;
     }
 
+    /**
+     * @param {OptionsCallback<object>} sassLoaderOptionsCallback
+     * @param {{resolveUrlLoader?: boolean, resolveUrlLoaderOptions?: object}} options
+     */
     enableSassLoader(sassLoaderOptionsCallback = () => {}, options = {}) {
         this.useSassLoader = true;
 
@@ -616,6 +721,9 @@ class WebpackConfig {
         }
     }
 
+    /**
+     * @param {OptionsCallback<object>} lessLoaderOptionsCallback
+     */
     enableLessLoader(lessLoaderOptionsCallback = () => {}) {
         this.useLessLoader = true;
 
@@ -626,6 +734,9 @@ class WebpackConfig {
         this.lessLoaderOptionsCallback = lessLoaderOptionsCallback;
     }
 
+    /**
+     * @param {OptionsCallback<object>} stylusLoaderOptionsCallback
+     */
     enableStylusLoader(stylusLoaderOptionsCallback = () => {}) {
         this.useStylusLoader = true;
 
@@ -656,6 +767,10 @@ class WebpackConfig {
         });
     }
 
+    /**
+     * @param {Record<string, string[]>} buildDependencies
+     * @param {OptionsCallback<webpack.FileCacheOptions>} callback
+     */
     enableBuildCache(buildDependencies, callback = (cache) => {}) {
         if (typeof buildDependencies !== 'object') {
             throw new Error('Argument 1 to enableBuildCache() must be an object.');
@@ -695,6 +810,9 @@ class WebpackConfig {
         this.useSvelte = true;
     }
 
+    /**
+     * @param {OptionsCallback<object>} callback
+     */
     enableTypeScriptLoader(callback = () => {}) {
         if (this.useBabelTypeScriptPreset) {
             throw new Error('Encore.enableTypeScriptLoader() can not be called when Encore.enableBabelTypeScriptPreset() has been called.');
@@ -709,6 +827,9 @@ class WebpackConfig {
         this.tsConfigurationCallback = callback;
     }
 
+    /**
+     * @param {OptionsCallback<object>} forkedTypeScriptTypesCheckOptionsCallback
+     */
     enableForkedTypeScriptTypesChecking(forkedTypeScriptTypesCheckOptionsCallback = () => {}) {
         if (this.useBabelTypeScriptPreset) {
             throw new Error('Encore.enableForkedTypeScriptTypesChecking() can not be called when Encore.enableBabelTypeScriptPreset() has been called.');
@@ -736,6 +857,10 @@ class WebpackConfig {
         this.babelTypeScriptPresetOptions = options;
     }
 
+    /**
+     * @param {OptionsCallback<object>} vueLoaderOptionsCallback
+     * @param {object} vueOptions
+     */
     enableVueLoader(vueLoaderOptionsCallback = () => {}, vueOptions = {}) {
         this.useVueLoader = true;
 
@@ -762,6 +887,10 @@ class WebpackConfig {
         }
     }
 
+    /**
+     * @param {boolean} enabled
+     * @param {OptionsCallback<object>} notifierPluginOptionsCallback
+     */
     enableBuildNotifications(enabled = true, notifierPluginOptionsCallback = () => {}) {
         if (typeof notifierPluginOptionsCallback !== 'function') {
             throw new Error('Argument 2 to enableBuildNotifications() must be a callback function.');
@@ -771,6 +900,9 @@ class WebpackConfig {
         this.notifierPluginOptionsCallback = notifierPluginOptionsCallback;
     }
 
+    /**
+     * @param {OptionsCallback<object>} callback
+     */
     enableHandlebarsLoader(callback = () => {}) {
         this.useHandlebarsLoader = true;
 
@@ -801,6 +933,10 @@ class WebpackConfig {
         this.configuredFilenames = configuredFilenames;
     }
 
+    /**
+     * @param {{filename?: string, maxSize?: number|null, type?: string, enabled?: boolean}} options
+     * @param {OptionsCallback<webpack.RuleSetRule>} ruleCallback
+     */
     configureImageRule(options = {}, ruleCallback = () => {}) {
         for (const optionKey of Object.keys(options)) {
             if (!(optionKey in this.imageRuleOptions)) {
@@ -821,6 +957,10 @@ class WebpackConfig {
         this.imageRuleCallback = ruleCallback;
     }
 
+    /**
+     * @param {{filename?: string, maxSize?: number|null, type?: string, enabled?: boolean}} options
+     * @param {OptionsCallback<webpack.RuleSetRule>} ruleCallback
+     */
     configureFontRule(options = {}, ruleCallback = () => {}) {
         for (const optionKey of Object.keys(options)) {
             if (!(optionKey in this.fontRuleOptions)) {
@@ -841,6 +981,9 @@ class WebpackConfig {
         this.fontRuleCallback = ruleCallback;
     }
 
+    /**
+     * @param {OptionsCallback<Exclude<ConstructorParameters<typeof webpack.CleanPlugin>[0], undefined>>} cleanOptionsCallback
+     */
     cleanupOutputBeforeBuild(cleanOptionsCallback = () => {}) {
         if (typeof cleanOptionsCallback !== 'function') {
             throw new Error('Argument 1 to cleanupOutputBeforeBuild() must be a callback function');
@@ -872,6 +1015,10 @@ class WebpackConfig {
         });
     }
 
+    /**
+     * @param {string} name
+     * @param {OptionsCallback<webpack.RuleSetRule>} callback
+     */
     configureLoaderRule(name, callback) {
         logger.warning('Be careful when using Encore.configureLoaderRule(), this is a low-level method that can potentially break Encore and Webpack when not used carefully.');
 
@@ -897,6 +1044,10 @@ class WebpackConfig {
         this.loaderConfigurationCallbacks[name] = callback;
     }
 
+    /**
+     * @param {boolean} enabled
+     * @param {string|string[]} algorithms
+     */
     enableIntegrityHashes(enabled = true, algorithms = ['sha384']) {
         if (!Array.isArray(algorithms)) {
             algorithms = [algorithms];
diff --git a/lib/config-generator.js b/lib/config-generator.js
index 31fd4c5f..c202cfc2 100644
--- a/lib/config-generator.js
+++ b/lib/config-generator.js
@@ -260,7 +260,7 @@ class ConfigGenerator {
     }
 
     /**
-     * @returns {import('webpack').CleanOptions|boolean}
+     * @returns {ConstructorParameters<typeof import('webpack').CleanPlugin>[0]|boolean}
      */
     buildCleanConfig() {
         if (!this.webpackConfig.cleanupOutput) {
diff --git a/lib/utils/apply-options-callback.js b/lib/utils/apply-options-callback.js
index cf1f11ba..c9eb0096 100644
--- a/lib/utils/apply-options-callback.js
+++ b/lib/utils/apply-options-callback.js
@@ -7,8 +7,19 @@
  * file that was distributed with this source code.
  */
 
+/**
+ * @typedef {function(this: T, T): T|void} OptionsCallback
+ * @template {object} T
+ */
+
 'use strict';
 
+/**
+ * @template {object} T
+ * @param {OptionsCallback<T>} optionsCallback
+ * @param {T} options
+ * @returns {T}
+ */
 module.exports = function(optionsCallback, options) {
     const result = optionsCallback.call(options, options);
 
diff --git a/lib/utils/package-up.js b/lib/utils/package-up.js
index 06097c01..f69457ae 100644
--- a/lib/utils/package-up.js
+++ b/lib/utils/package-up.js
@@ -16,13 +16,18 @@ const { fileURLToPath } = require('url');
 /**
  * Inlined version of the package "package-up" (ESM only).
  *
- * @param {string} cwd The directory to start searching from.
+ * @param {object} options
+ * @param {string} options.cwd The directory to start searching from.
  * @returns {string|undefined} The path to the nearest package.json file or undefined if not found.
  */
 module.exports = function({ cwd }) {
     return findUpSync('package.json', { cwd, type: 'file' });
 };
 
+/**
+ * @param {string|URL} urlOrPath
+ * @returns {string}
+ */
 function toPath(urlOrPath) {
     return urlOrPath instanceof URL ? fileURLToPath(urlOrPath) : urlOrPath;
 }
@@ -32,7 +37,7 @@ function toPath(urlOrPath) {
  *
  * @param {string} name The name of the file to find
  * @param {object} options
- * @param {string} options.cwd The directory to start searching from.
+ * @param {string=} options.cwd The directory to start searching from.
  * @returns {string|undefined} The path to the file found or undefined if not found.
  */
 function findUpSync(name, { cwd = process.cwd() } = {}) {