Skip loading clerk-ui when headless variants are used

integration/templates/next-app-router/src/app/layout.tsx

@@ -12,6 +12,7 @@ export const metadata = {
 export default function RootLayout({ children }: { children: React.ReactNode }) {
   return (
     <ClerkProvider
+      clerkJSVariant={process.env.NEXT_PUBLIC_CLERK_JS_VARIANT === 'headless' ? 'headless' : undefined}
       appearance={{
         options: {
           showOptionalFields: true,

integration/tests/headless-variant.test.ts

@@ -0,0 +1,32 @@
+import { expect, test } from '@playwright/test';
+
+import type { Application } from '../models/application';
+import { appConfigs } from '../presets';
+
+test.describe('headless variant @nextjs', () => {
+  test.describe.configure({ mode: 'serial' });
+  let app: Application;
+
+  test.beforeAll(async () => {
+    app = await appConfigs.next.appRouter.clone().commit();
+    await app.setup();
+    // Use withEmailCodes but add the headless variant
+    const env = appConfigs.envs.withEmailCodes.clone().setEnvVariable('public', 'CLERK_JS_VARIANT', 'headless');
+    await app.withEnv(env);
+    await app.dev();
+  });
+
+  test.afterAll(async () => {
+    await app.teardown();
+  });
+
+  test('does not inject clerk-ui script when headless variant is used', async ({ page }) => {
+    await page.goto(app.serverUrl);
+
+    // Wait for clerk-js script to be present (ensures page has loaded)
+    await expect(page.locator('script[data-clerk-js-script]')).toBeAttached();
+
+    // clerk-ui script should NOT be present
+    await expect(page.locator('script[data-clerk-ui-script]')).not.toBeAttached();
+  });
+});

packages/astro/src/internal/create-clerk-instance.ts

@@ -111,10 +111,16 @@ async function getClerkJsEntryChunk<TUi extends Ui = Ui>(options?: AstroClerkCre
 /**
  * Gets the ClerkUI constructor, either from options or by loading the script.
  * Returns early if window.__internal_ClerkUiCtor already exists.
+ * Returns undefined for headless variant (no UI needed).
  */
 async function getClerkUiEntryChunk<TUi extends Ui = Ui>(
   options?: AstroClerkCreateInstanceParams<TUi>,
-): Promise<ClerkUiConstructor> {
+): Promise<ClerkUiConstructor | undefined> {
+  // Skip UI loading for headless variant
+  if (options?.clerkJSVariant === 'headless') {
+    return undefined;
+  }
+
   if (options?.clerkUiCtor) {
     return options.clerkUiCtor;
   }

packages/astro/src/server/build-clerk-hotload-script.ts

@@ -10,37 +10,49 @@ function buildClerkHotloadScript(locals: APIContext['locals']) {
   const proxyUrl = getSafeEnv(locals).proxyUrl!;
   // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
   const domain = getSafeEnv(locals).domain!;
+  const clerkJsVariant = getSafeEnv(locals).clerkJsVariant;
   const clerkJsScriptSrc = clerkJsScriptUrl({
     clerkJSUrl: getSafeEnv(locals).clerkJsUrl,
-    clerkJSVariant: getSafeEnv(locals).clerkJsVariant,
+    clerkJSVariant: clerkJsVariant,
     clerkJSVersion: getSafeEnv(locals).clerkJsVersion,
     domain,
     proxyUrl,
     publishableKey,
   });
-  const clerkUiScriptSrc = clerkUiScriptUrl({
-    clerkUiUrl: getSafeEnv(locals).clerkUiUrl,
-    domain,
-    proxyUrl,
-    publishableKey,
-  });
-  return `
+
+  const clerkJsScript = `
   <script src="${clerkJsScriptSrc}"
   data-clerk-js-script
   async
   crossOrigin='anonymous'
   ${publishableKey ? `data-clerk-publishable-key="${publishableKey}"` : ``}
   ${proxyUrl ? `data-clerk-proxy-url="${proxyUrl}"` : ``}
   ${domain ? `data-clerk-domain="${domain}"` : ``}
-  ></script>
+  ></script>`;
+
+  // Skip clerk-ui script for headless variant
+  if (clerkJsVariant === 'headless') {
+    return clerkJsScript + '\n';
+  }
+
+  const clerkUiScriptSrc = clerkUiScriptUrl({
+    clerkUiUrl: getSafeEnv(locals).clerkUiUrl,
+    domain,
+    proxyUrl,
+    publishableKey,
+  });
+
+  const clerkUiScript = `
   <script src="${clerkUiScriptSrc}"
   data-clerk-ui-script
   async
   crossOrigin='anonymous'
   ${publishableKey ? `data-clerk-publishable-key="${publishableKey}"` : ``}
   ${proxyUrl ? `data-clerk-proxy-url="${proxyUrl}"` : ``}
   ${domain ? `data-clerk-domain="${domain}"` : ``}
-  ></script>\n`;
+  ></script>`;
+
+  return clerkJsScript + clerkUiScript + '\n';
 }
 
 export { buildClerkHotloadScript };

packages/nextjs/src/utils/clerk-script.tsx

@@ -70,12 +70,14 @@ export function ClerkScripts({ router }: { router: ClerkScriptProps['router'] })
         dataAttribute='data-clerk-js-script'
         router={router}
       />
-      <ClerkScript
-        scriptUrl={clerkUiScriptUrl(opts)}
-        attributes={buildClerkUiScriptAttributes(opts)}
-        dataAttribute='data-clerk-ui-script'
-        router={router}
-      />
+      {clerkJSVariant !== 'headless' && (
+        <ClerkScript
+          scriptUrl={clerkUiScriptUrl(opts)}
+          attributes={buildClerkUiScriptAttributes(opts)}
+          dataAttribute='data-clerk-ui-script'
+          router={router}
+        />
+      )}
     </>
   );
 }

packages/react/src/isomorphicClerk.ts

@@ -508,7 +508,12 @@ export class IsomorphicClerk implements IsomorphicLoadedClerk {
     return global.Clerk;
   }
 
-  private async getClerkUiEntryChunk(): Promise<ClerkUiConstructor> {
+  private async getClerkUiEntryChunk(): Promise<ClerkUiConstructor | undefined> {
+    // Skip UI loading for headless variant
+    if (this.options.clerkJSVariant === 'headless') {
+      return undefined;
+    }
+
     if (this.options.clerkUiCtor) {
       return this.options.clerkUiCtor;
     }

packages/vue/src/plugin.ts

@@ -78,15 +78,19 @@ export const clerkPlugin: Plugin<[PluginOptions]> = {
       void (async () => {
         try {
           const clerkPromise = loadClerkJsScript(options);
-          const clerkUiCtorPromise = pluginOptions.clerkUiCtor
-            ? Promise.resolve(pluginOptions.clerkUiCtor)
-            : (async () => {
-                await loadClerkUiScript(options);
-                if (!window.__internal_ClerkUiCtor) {
-                  throw new Error('Failed to download latest Clerk UI. Contact [email protected].');
-                }
-                return window.__internal_ClerkUiCtor;
-              })();
+          // Skip UI loading for headless variant
+          const clerkUiCtorPromise =
+            pluginOptions.clerkJSVariant === 'headless'
+              ? Promise.resolve(undefined)
+              : pluginOptions.clerkUiCtor
+                ? Promise.resolve(pluginOptions.clerkUiCtor)
+                : (async () => {
+                    await loadClerkUiScript(options);
+                    if (!window.__internal_ClerkUiCtor) {
+                      throw new Error('Failed to download latest Clerk UI. Contact [email protected].');
+                    }
+                    return window.__internal_ClerkUiCtor;
+                  })();
 
           await clerkPromise;