diff --git a/packages/overlayscrollbars-jquery/build.config.json b/packages/overlayscrollbars-jquery/build.config.json
index 6f292ff..3f4e621 100644
--- a/packages/overlayscrollbars-jquery/build.config.json
+++ b/packages/overlayscrollbars-jquery/build.config.json
@@ -1,9 +1,7 @@
 {
-  "legacy": {
-    "name": "OverlayScrollbars",
-    "exports": "auto",
-    "globals": {
-      "jquery": "jQuery"
-    }
+  "name": "OverlayScrollbars",
+  "exports": "auto",
+  "globals": {
+    "jquery": "jQuery"
   }
 }
diff --git a/packages/overlayscrollbars/build.config.json b/packages/overlayscrollbars/build.config.json
index 6f292ff..3f4e621 100644
--- a/packages/overlayscrollbars/build.config.json
+++ b/packages/overlayscrollbars/build.config.json
@@ -1,9 +1,7 @@
 {
-  "legacy": {
-    "name": "OverlayScrollbars",
-    "exports": "auto",
-    "globals": {
-      "jquery": "jQuery"
-    }
+  "name": "OverlayScrollbars",
+  "exports": "auto",
+  "globals": {
+    "jquery": "jQuery"
   }
 }
diff --git a/rollup.config.js b/rollup.config.js
index 2a36d43..6c96ff2 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -10,6 +10,7 @@ import path from 'path';
 import resolve from './resolve.config.json';
 
 const projectRootPath = './packages';
+const buildConfigNames = ['build.config.js', 'build.config.json'];
 
 const legacyBabelConfig = {
   presets: [
@@ -40,40 +41,52 @@ const esmBabelConfig = {
   ],
 };
 
-export default async (config) => {
+const getBuildConfig = (projectPath) => {
+  const buildConfigName = buildConfigNames.find((name) => fs.existsSync(path.resolve(projectPath, name)));
+  return buildConfigName ? path.resolve(projectPath, buildConfigName) : '';
+};
+
+export default async (config, overwriteBuildConfig) => {
   const { 'config-project': project } = config;
 
   const defaultInputName = './src/index';
   const projectPath = path.resolve(__dirname, projectRootPath, project);
   const packageJSONPath = path.resolve(projectPath, 'package.json');
   const tsconfigJSONPath = path.resolve(projectPath, 'tsconfig.json');
-  const buildConfigPath = path.resolve(projectPath, 'build.config.json');
+  const buildConfigPath = getBuildConfig(projectPath);
   const isTypeScriptProject = fs.existsSync(tsconfigJSONPath);
+  const buildConfigDefaults = {
+    input: defaultInputName + resolve.extensions.find((ext) => fs.existsSync(path.resolve(projectPath, `${defaultInputName}${ext}`))),
+    src: './src',
+    dist: './dist',
+    types: './types',
+    tests: './tests',
+    cache: [],
+    minVersions: true,
+    sourcemap: true,
+    esmBuild: true,
+    name: project,
+    exports: 'auto',
+  };
+  const buildConfig = {
+    ...buildConfigDefaults,
+    ...(await import(buildConfigPath)),
+    ...(overwriteBuildConfig || {}),
+  };
 
-  const {
-    input = defaultInputName + resolve.extensions.find((ext) => fs.existsSync(path.resolve(projectPath, `${defaultInputName}${ext}`))),
-    src = './src',
-    dist = './dist',
-    types = './types',
-    tests = './tests',
-    cache = [],
-    minVersions = true,
-    modules: { sourcemap: modulesSourceMap = true } = {},
-    legacy: { sourcemap: legacySourceMap = true, exports = 'auto', name = project, globals } = {},
-  } = await import(buildConfigPath);
-
+  const { input, src, dist, types, tests, cache, minVersions, sourcemap, esmBuild, name, exports, globals } = buildConfig;
   const { devDependencies = {}, peerDependencies = {} } = await import(packageJSONPath);
 
-  const srcPath = path.resolve(projectPath, src);
-  const distPath = path.resolve(projectPath, dist);
-  const typesPath = path.resolve(projectPath, types);
-  const testsPath = path.resolve(projectPath, tests);
-  const inputPath = path.resolve(projectPath, input);
+  const srcPath = src ? path.resolve(projectPath, src) : null;
+  const distPath = dist ? path.resolve(projectPath, dist) : null;
+  const typesPath = types ? path.resolve(projectPath, types) : null;
+  const testsPath = tests ? path.resolve(projectPath, tests) : null;
+  const inputPath = input ? path.resolve(projectPath, input) : null;
 
   const genOutputConfig = (esm) => ({
     format: esm ? 'esm' : 'umd',
     file: path.resolve(distPath, `${project}${esm ? '.esm' : ''}.js`),
-    sourcemap: esm ? modulesSourceMap : legacySourceMap,
+    sourcemap,
     ...(esm
       ? {}
       : {
@@ -83,12 +96,12 @@ export default async (config) => {
         }),
     plugins: [
       rollupPrettier({
-        sourcemap: (esm ? modulesSourceMap : legacySourceMap) && 'silent',
+        sourcemap: sourcemap && 'silent',
       }),
     ],
   });
 
-  const genConfig = async ({ esm, typeDeclaration }, ...plugins) => {
+  const genConfig = async ({ esm, typeDeclaration }) => {
     const output = genOutputConfig(esm);
     return {
       input: inputPath,
@@ -111,7 +124,6 @@ export default async (config) => {
       ),
       external: [...Object.keys(devDependencies), ...Object.keys(peerDependencies)],
       plugins: [
-        ...plugins,
         rollupResolve({
           extensions: resolve.extensions,
           rootDir: srcPath,
@@ -129,7 +141,7 @@ export default async (config) => {
                 compilerOptions: {
                   target: 'ESNext',
                   sourceMap: true,
-                  declaration: typeDeclaration,
+                  declaration: typeDeclaration && types !== null,
                   declarationDir: typesPath,
                 },
                 exclude: ((await import(tsconfigJSONPath)).exclude || []).concat(testsPath),
@@ -147,33 +159,44 @@ export default async (config) => {
 
   console.log('');
   console.log('PROJECT : ', project);
-  console.log('NODE_ENV: ', process.env.NODE_ENV);
+  console.log('ENV     : ', process.env.NODE_ENV);
+  console.log('CONFIG  : ', buildConfig);
 
-  return [
-    await genConfig(
-      { esm: false, typeDeclaration: true },
-      {
-        name: 'deleteGeneratedDirs',
-        options() {
-          const deletedDirs = del.sync([distPath, typesPath]);
-          if (deletedDirs.length > 0) {
-            console.log('Deleted directories:\n', deletedDirs.join('\n'));
-          }
-        },
+  const legacy = await genConfig({ esm: false, typeDeclaration: true });
+  const esm = esmBuild ? await genConfig({ esm: true, typeDeclaration: false }) : null;
+
+  const builds = [legacy, esm]
+    .filter((build) => build !== null)
+    .map((build, index, buildsArr) => {
+      const isFirst = index === 0;
+      const isLast = index === buildsArr.length - 1;
+
+      if (isFirst) {
+        build.plugins.unshift({
+          name: 'deleteGeneratedDirs',
+          options() {
+            const deletedDirs = del.sync([distPath, typesPath].filter((curr) => curr !== null));
+            if (deletedDirs.length > 0) {
+              console.log('Deleted directories:\n', deletedDirs.join('\n'));
+            }
+          },
+        });
       }
-    ),
-    await genConfig(
-      { esm: true, typeDeclaration: false },
-      {
-        name: 'deleteCacheDirs',
-        writeBundle() {
-          const cacheDirs = cache.map((dir) => path.resolve(projectPath, dir));
-          const deletedDirs = del.sync(cacheDirs);
-          if (deletedDirs.length > 0) {
-            console.log('Deleted cache:\n', deletedDirs.join('\n'));
-          }
-        },
+      if (isLast) {
+        build.plugins.unshift({
+          name: 'deleteCacheDirs',
+          writeBundle() {
+            const cacheDirs = cache.map((dir) => path.resolve(projectPath, dir));
+            const deletedDirs = del.sync(cacheDirs);
+            if (deletedDirs.length > 0) {
+              console.log('Deleted cache:\n', deletedDirs.join('\n'));
+            }
+          },
+        });
       }
-    ),
-  ];
+
+      return build;
+    });
+
+  return builds;
 };