diff --git a/packages/common/src/index.ts b/packages/common/src/index.ts
index d25acd7..90bc434 100644
--- a/packages/common/src/index.ts
+++ b/packages/common/src/index.ts
@@ -38,6 +38,50 @@ export class BundleUpCore {
   getConfig(): BundleUpConfig {
     return { ...this.config };
   }
+
+  /**
+   * Backend method to request an authentication token
+   * @param integrationId - The integration ID provided by user
+   * @param externalId - The external ID provided by user
+   * @returns Promise<string> - The authentication token
+   */
+  async requestAuthToken(integrationId: string, externalId: string): Promise<string> {
+    if (!this.config.apiKey) {
+      throw new Error('API key is required for authentication');
+    }
+
+    this.log('Requesting authentication token', { integrationId, externalId });
+
+    try {
+      const response = await fetch('https://auth.bundleup.io/authorize', {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+          'Authorization': `Bearer ${this.config.apiKey}`,
+        },
+        body: JSON.stringify({
+          integrationId,
+          externalId,
+        }),
+      });
+
+      if (!response.ok) {
+        throw new Error(`Authentication request failed: ${response.status} ${response.statusText}`);
+      }
+
+      const data: any = await response.json();
+      
+      if (!data.token) {
+        throw new Error('Invalid response: token not found');
+      }
+
+      this.log('Authentication token received successfully');
+      return data.token;
+    } catch (error) {
+      this.log('Authentication token request failed', error);
+      throw error;
+    }
+  }
 }
 
 export function createBundleUpPlugin(options: PluginOptions = {}) {
diff --git a/packages/common/src/types.ts b/packages/common/src/types.ts
index 885a9a7..c4ee918 100644
--- a/packages/common/src/types.ts
+++ b/packages/common/src/types.ts
@@ -10,4 +10,13 @@ export interface BundleMetrics {
   gzipSize: number;
   modules: number;
   chunks: number;
+}
+
+export interface AuthenticationRequest {
+  integrationId: string;
+  externalId: string;
+}
+
+export interface AuthenticationResponse {
+  token: string;
 }
\ No newline at end of file
diff --git a/packages/react/src/index.ts b/packages/react/src/index.ts
index af3c234..d403f25 100644
--- a/packages/react/src/index.ts
+++ b/packages/react/src/index.ts
@@ -26,6 +26,111 @@ export class ReactBundleUpPlugin extends BundleUpCore {
       };
     };
   }
+
+  /**
+   * Frontend method to open popup window for authentication
+   * @param token - Authentication token obtained from backend
+   * @returns Promise<void> - Resolves when authentication is complete
+   */
+  async authenticateWithPopup(token: string): Promise<void> {
+    return new Promise((resolve, reject) => {
+      if (!token) {
+        reject(new Error('Token is required for authentication'));
+        return;
+      }
+
+      this.log('Opening authentication popup with token');
+
+      // Check if we're in a browser environment
+      if (typeof window === 'undefined') {
+        reject(new Error('Authentication popup is only available in browser environment'));
+        return;
+      }
+
+      // Open popup window
+      const popup = window.open(
+        `https://auth.bundleup.io/${token}`,
+        'bundleup-auth',
+        'width=500,height=600,scrollbars=yes,resizable=yes'
+      );
+
+      if (!popup) {
+        reject(new Error('Failed to open popup window. Please check popup blocker settings.'));
+        return;
+      }
+
+      // Listen for messages from popup
+      const handleMessage = (event: MessageEvent) => {
+        // Security check: verify origin
+        if (event.origin !== 'https://auth.bundleup.io') {
+          return;
+        }
+
+        this.log('Received message from authentication popup', event.data);
+
+        if (event.data && event.data.type === 'bundleup-auth-success') {
+          // Authentication successful
+          cleanup();
+          popup.close();
+          this.log('Authentication completed successfully');
+          resolve();
+        } else if (event.data && event.data.type === 'bundleup-auth-error') {
+          // Authentication failed
+          cleanup();
+          popup.close();
+          this.log('Authentication failed', event.data.error);
+          reject(new Error(event.data.error || 'Authentication failed'));
+        }
+      };
+
+      // Check if popup is closed manually
+      const checkClosed = setInterval(() => {
+        if (popup.closed) {
+          cleanup();
+          reject(new Error('Authentication popup was closed by user'));
+        }
+      }, 1000);
+
+      const cleanup = () => {
+        window.removeEventListener('message', handleMessage);
+        clearInterval(checkClosed);
+      };
+
+      // Add message listener
+      window.addEventListener('message', handleMessage);
+
+      // Handle popup blocked or closed immediately
+      setTimeout(() => {
+        if (popup.closed) {
+          cleanup();
+          reject(new Error('Popup was blocked or closed immediately'));
+        }
+      }, 100);
+    });
+  }
+
+  /**
+   * Complete authentication flow: request token and open popup
+   * @param integrationId - The integration ID
+   * @param externalId - The external ID
+   * @returns Promise<void> - Resolves when authentication is complete
+   */
+  async authenticate(integrationId: string, externalId: string): Promise<void> {
+    try {
+      this.log('Starting complete authentication flow');
+      
+      // Step 1: Request token from backend
+      const token = await this.requestAuthToken(integrationId, externalId);
+      
+      // Step 2: Open popup with token
+      await this.authenticateWithPopup(token);
+      
+      this.log('Authentication flow completed successfully');
+    } catch (error) {
+      this.log('Authentication flow failed', error);
+      throw error;
+    }
+  }
 }
 
 export function createReactBundleUpPlugin(options: ReactBundleUpOptions = {}) {
@@ -34,13 +139,36 @@ export function createReactBundleUpPlugin(options: ReactBundleUpOptions = {}) {
 
 // React Hook for BundleUp integration
 export function useBundleUp(config?: BundleUpConfig) {
-  const bundleUp = useRef<BundleUpCore>();
+  const bundleUp = useRef<ReactBundleUpPlugin>();
   
   if (!bundleUp.current) {
-    bundleUp.current = new BundleUpCore(config);
+    bundleUp.current = new ReactBundleUpPlugin({ bundleUpConfig: config });
   }
 
   return bundleUp.current;
 }
 
+// React Hook for authentication
+export function useBundleUpAuth(config?: BundleUpConfig) {
+  const bundleUp = useBundleUp(config);
+
+  const authenticate = async (integrationId: string, externalId: string): Promise<void> => {
+    return bundleUp.authenticate(integrationId, externalId);
+  };
+
+  const authenticateWithToken = async (token: string): Promise<void> => {
+    return bundleUp.authenticateWithPopup(token);
+  };
+
+  const requestToken = async (integrationId: string, externalId: string): Promise<string> => {
+    return bundleUp.requestAuthToken(integrationId, externalId);
+  };
+
+  return {
+    authenticate,
+    authenticateWithToken,
+    requestToken,
+  };
+}
+
 export * from '@bundleup/common';
\ No newline at end of file
diff --git a/packages/react/tsconfig.json b/packages/react/tsconfig.json
index 4af17f9..7340615 100644
--- a/packages/react/tsconfig.json
+++ b/packages/react/tsconfig.json
@@ -2,7 +2,8 @@
   "extends": "../../tsconfig.json",
   "compilerOptions": {
     "outDir": "./dist",
-    "rootDir": "./src"
+    "rootDir": "./src",
+    "lib": ["ES2020", "DOM"]
   },
   "include": ["src/**/*"],
   "exclude": ["node_modules", "dist", "**/*.test.*"]