diff --git a/src/helpers.ts b/src/helpers.ts
index ceadc7d..b6cd80f 100644
--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -1,22 +1,22 @@
 import { transformWithEsbuild } from 'vite'
 import { grants } from './constants.js'
 import type { Grants, Transform } from './types.js'
+import type { EsbuildTransformOptions } from 'vite'
 
 export function removeDuplicates(arr: any): any[] {
   return [...new Set(Array.isArray(arr) ? arr : arr ? [arr] : [])]
 }
 
-export async function transform({
-  minify,
-  file,
-  name,
-  loader
-}: Transform): Promise<string> {
+export async function transform(
+  { minify, file, name, loader }: Transform,
+  transformOptions?: EsbuildTransformOptions
+): Promise<string> {
   const { code } = await transformWithEsbuild(file, name, {
     minify,
     loader,
     sourcemap: false,
-    legalComments: 'none'
+    legalComments: 'none',
+    ...transformOptions
   })
 
   return code
diff --git a/src/index.ts b/src/index.ts
index 8313137..66b77b9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -148,12 +148,15 @@ export default function UserscriptPlugin(
             try {
               let source = readFileSync(outPath, 'utf8')
               source = source.replace(styleTemplate, `${css.inject()}`)
-              source = await transform({
-                minify: !isBuildWatch,
-                file: source,
-                name: fileName,
-                loader: 'js'
-              })
+              source = await transform(
+                {
+                  minify: !isBuildWatch,
+                  file: source,
+                  name: fileName,
+                  loader: 'js'
+                },
+                config.esbuildTransformOptions
+              )
 
               config.header.grant = removeDuplicates(
                 isBuildWatch
@@ -164,12 +167,15 @@ export default function UserscriptPlugin(
               if (isBuildWatch) {
                 const wsFile = readFileSync(resolve(pluginDir, 'ws.js'), 'utf8')
 
-                const wsScript = await transform({
-                  minify: !isBuildWatch,
-                  file: wsFile.replace('__WS__', `ws://localhost:${port}`),
-                  name: wsPath,
-                  loader: 'js'
-                })
+                const wsScript = await transform(
+                  {
+                    minify: !isBuildWatch,
+                    file: wsFile.replace('__WS__', `ws://localhost:${port}`),
+                    name: wsPath,
+                    loader: 'js'
+                  },
+                  config.esbuildTransformOptions
+                )
 
                 writeFileSync(wsPath, wsScript)
                 writeFileSync(
diff --git a/src/types.ts b/src/types.ts
index 9068d07..b75e37e 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,4 +1,5 @@
 import { GM, GMwindow } from './constants.js'
+import type { EsbuildTransformOptions } from 'vite'
 
 export interface Transform {
   minify: boolean
@@ -217,4 +218,20 @@ export interface UserscriptPluginConfig {
    * Server config.
    */
   server?: ServerConfig
+
+  /**
+   * Override default esbuild transform options.
+   *
+   * @default
+   * ```json
+   * {
+   *   "minify": true,
+   *   "legalComments": "none"
+   * }
+   * ```
+   */
+  esbuildTransformOptions?: Omit<
+    EsbuildTransformOptions,
+    'format' | 'target' | 'loader' | 'sourcemap'
+  >
 }