diff --git a/src/front/Stores/WindowStore.ts b/src/front/Stores/WindowStore.ts
index d15a1538..42abcabb 100644
--- a/src/front/Stores/WindowStore.ts
+++ b/src/front/Stores/WindowStore.ts
@@ -36,6 +36,10 @@ export default class WindowStore {
 	}
 
 	private iniEvents(): void {
+		if (typeof window === 'undefined' || typeof document === 'undefined') {
+			// SSR: do not bind browser events
+			return;
+		}
 		window.addEventListener("scroll", (e: Event) => this.scrollYHandler());
 		window.addEventListener("resize", (e: Event) => this.resizeHandler());
 		document.addEventListener("click", (e: MouseEvent) => this.clickHandler(e), true);
@@ -46,10 +50,11 @@ export default class WindowStore {
 	}
 
 	private scrollYHandler = (() => {
-		let previousY: number = window.scrollY;
+		let previousY: number = (typeof window !== 'undefined' ? window.scrollY : 0);
 		let snapShotY: number = previousY;
 		let previousYDirection: number = 1;
 		return (): void => {
+			if (typeof window === 'undefined') return;
 			const scrollYDirection = window.scrollY - previousY > 0 ? 1 : -1;
 			if (previousYDirection !== scrollYDirection) {
 				snapShotY = window.scrollY;
@@ -62,6 +67,7 @@ export default class WindowStore {
 	})();
 
 	private resizeHandler() {
+		if (typeof window === 'undefined') return;
 		this.event.emit("resize", window);
 	}
 }
diff --git a/src/pages/_app.tsx b/src/pages/_app.tsx
index 4597a416..61464e44 100644
--- a/src/pages/_app.tsx
+++ b/src/pages/_app.tsx
@@ -6,11 +6,13 @@ import type { AppType, AppProps } from "next/app";
 import { useEffect, useState, type ReactElement, type ReactNode } from "react";
 import getConfig from "next/config";
 import { GoogleTagManager } from "@next/third-parties/google";
+import dynamic from 'next/dynamic';
 
 import Loader from "src/common/Api/LeCoffreApi/sdk/Loader";
 
 import IframeReference from "src/sdk/IframeReference";
-import Iframe from "src/sdk/Iframe";
+// import Iframe from "src/sdk/Iframe";
+const IframeNoSSR = dynamic(() => import('src/sdk/Iframe'), { ssr: false });
 import MessageBus from "src/sdk/MessageBus";
 import User from "src/sdk/User";
 
@@ -80,26 +82,31 @@ const MyApp = (({
 
 	const [isConnected, setIsConnected] = useState(false);
 	const [isReady, setIsReady] = useState(false);
+	const [mounted, setMounted] = useState(false);
 
-    const targetOrigin = (() => {
-        try {
-            return new URL(_4nkUrl).origin;
-        } catch {
-            return _4nkUrl;
-        }
-    })();
-    IframeReference.setTargetOrigin(targetOrigin);
+	// Configure iframe target and URL on client-side only
+	useEffect(() => {
+		setMounted(true);
+		try {
+			if (_4nkUrl && typeof _4nkUrl === 'string' && _4nkUrl.trim().length > 0) {
+				const origin = (() => {
+					try { return new URL(_4nkUrl).origin; } catch { return _4nkUrl; }
+				})();
+				IframeReference.setTargetOrigin(origin);
 
-    // Configure full iframe URL if provided (falls back to origin)
-    const iframeUrl = (() => {
-        const candidate = (publicRuntimeConfig as any).NEXT_PUBLIC_4NK_IFRAME_URL ?? _4nkUrl;
-        try {
-            return new URL(candidate).toString();
-        } catch {
-            return targetOrigin;
-        }
-    })();
-    IframeReference.setIframeUrl(iframeUrl);
+				const candidate = (publicRuntimeConfig as any).NEXT_PUBLIC_4NK_IFRAME_URL ?? _4nkUrl;
+				const iframe = (() => {
+					try { return new URL(candidate).toString(); } catch { return origin; }
+				})();
+				IframeReference.setIframeUrl(iframe);
+			} else {
+				console.warn('[MyApp] NEXT_PUBLIC_4NK_URL is missing; skipping iframe setup');
+			}
+		} catch (e) {
+			console.error('[MyApp] Failed to initialize IframeReference', e);
+		}
+		// eslint-disable-next-line react-hooks/exhaustive-deps
+	}, []);
 
 	useEffect(() => {
 		const isAuthenticated = User.getInstance().isAuthenticated();
@@ -117,7 +124,12 @@ const MyApp = (({
 		return () => { };
 	}, []);
 
-    // Hotjar supprimé
+	// Empêcher le rendu SSR du contenu qui dépend du navigateur
+	if (!mounted) {
+		return <Loader />;
+	}
+
+	// Hotjar supprimé
 
 	return getLayout(
 		<>
@@ -126,7 +138,7 @@ const MyApp = (({
 					<GoogleTagManager gtmId="GTM-5GLJN86P" />
 				</Component>
 			}
-			{isConnected && <Iframe />}
+			{isConnected && <IframeNoSSR />}
 			<Loader />
 		</>
 	);
@@ -147,7 +159,7 @@ MyApp.getInitialProps = async () => {
 		idNotRedirectUri: publicRuntimeConfig.NEXT_PUBLIC_IDNOT_REDIRECT_URI,
 		fcAuthorizeEndpoint: publicRuntimeConfig.NEXT_PUBLIC_FC_AUTHORIZE_ENDPOINT,
 		fcClientId: publicRuntimeConfig.NEXT_PUBLIC_FC_CLIENT_ID,
-		docaposteApiUrl: publicRuntimeConfig.NEXT_PUBLIC_DOCAPOST_API_URL,
+		docaposteApiUrl: publicRuntimeConfig.NEXT_PUBLIC_DOCAPOSTE_API_URL,
 		_4nkUrl: publicRuntimeConfig.NEXT_PUBLIC_4NK_URL,
 		_4nkIframeUrl: publicRuntimeConfig.NEXT_PUBLIC_4NK_IFRAME_URL,
 		apiUrl: publicRuntimeConfig.NEXT_PUBLIC_API_URL,
diff --git a/src/sdk/AuthModal.tsx b/src/sdk/AuthModal.tsx
index 4fb132a4..fecb6752 100644
--- a/src/sdk/AuthModal.tsx
+++ b/src/sdk/AuthModal.tsx
@@ -17,10 +17,23 @@ export default function AuthModal({ isOpen, onClose }: AuthModalProps) {
   const [isIframeReady, setIsIframeReady] = useState(false);
   const [showIframe, setShowIframe] = useState(false);
   const [authSuccess, setAuthSuccess] = useState(false);
+  const [iframeSrc, setIframeSrc] = useState<string | null>(null);
 
   const iframeRef = useRef<HTMLIFrameElement>(null);
 
+  // Initialize iframe URL client-side only
   useEffect(() => {
+    try {
+      const url = IframeReference.getIframeUrl();
+      setIframeSrc(url);
+    } catch {
+      setIframeSrc(null);
+    }
+  }, []);
+
+  useEffect(() => {
+    if (typeof window === 'undefined') return;
+
     const handleMessage = (event: MessageEvent) => {
       if (!event.data || event.data.type === 'PassClientScriptReady') {
         return;
@@ -31,15 +44,20 @@ export default function AuthModal({ isOpen, onClose }: AuthModalProps) {
         return;
       }
 
-      const targetOrigin = IframeReference.getTargetOrigin();
-      if (!targetOrigin) {
+      let targetOrigin: string | null = null;
+      try {
+        targetOrigin = IframeReference.getTargetOrigin();
+      } catch {
         console.error('[AuthModal] handleMessage: targetOrigin not found');
         return;
       }
 
+      if (!targetOrigin) {
+        return;
+      }
+
       // Accepter seulement les messages de l'iframe (même origine)
       if (event.origin !== targetOrigin) {
-        // Ignorer silencieusement les messages des DevTools et autres sources
         return;
       }
 
@@ -58,7 +76,6 @@ export default function AuthModal({ isOpen, onClose }: AuthModalProps) {
           setIsIframeReady(true);
           break;
         }
-
         case 'LINK_ACCEPTED': {
           setShowIframe(false);
           User.getInstance().setTokens(message.accessToken, message.refreshToken);
@@ -66,12 +83,10 @@ export default function AuthModal({ isOpen, onClose }: AuthModalProps) {
           iframeRef.current.contentWindow!.postMessage({ type: 'GET_PAIRING_ID', accessToken: message.accessToken, messageId }, targetOrigin);
           break;
         }
-
         case 'PAIRING_CREATED': {
           console.log('[AuthModal] PAIRING_CREATED:', message);
           User.getInstance().setPairingId(message.userPairingId);
           setAuthSuccess(true);
-
           setTimeout(() => {
             setShowIframe(false);
             setIsIframeReady(false);
@@ -80,11 +95,9 @@ export default function AuthModal({ isOpen, onClose }: AuthModalProps) {
           }, 500);
           break;
         }
-
         case 'GET_PAIRING_ID': {
           User.getInstance().setPairingId(message.userPairingId);
           setAuthSuccess(true);
-
           setTimeout(() => {
             setShowIframe(false);
             setIsIframeReady(false);
@@ -93,28 +106,21 @@ export default function AuthModal({ isOpen, onClose }: AuthModalProps) {
           }, 500);
           break;
         }
-
         case 'ERROR': {
           console.error('[AuthModal] handleMessage: error', message);
-          if (message.messageId.includes('GET_PAIRING_ID')) {
-            // We are not paired yet
+          if (message.messageId?.includes('GET_PAIRING_ID')) {
             const accessToken = User.getInstance().getAccessToken();
             if (accessToken) {
-              // create a new pairing
               const messageId = `CREATE_PAIRING_${uuidv4()}`;
               iframeRef.current.contentWindow!.postMessage({ type: 'CREATE_PAIRING', accessToken, messageId }, targetOrigin);
             } else {
-              // We don't have an access token
-              // Shouldn't happen
-              console.error('[AuthModal] handleMessage: error: we don\'t have an access token');
+              console.error("[AuthModal] handleMessage: error: we don't have an access token");
               setShowIframe(false);
               setIsIframeReady(false);
               setAuthSuccess(false);
               onClose();
             }
-          } else if (message.messageId.includes('CREATE_PAIRING')) {
-            // Something went wrong while creating a pairing
-            // show stopper for now
+          } else if (message.messageId?.includes('CREATE_PAIRING')) {
             console.error('[AuthModal] CREATE_PAIRING error:', message.error);
             setShowIframe(false);
             setIsIframeReady(false);
@@ -125,8 +131,8 @@ export default function AuthModal({ isOpen, onClose }: AuthModalProps) {
         }
       }
     };
-    window.addEventListener('message', handleMessage);
 
+    window.addEventListener('message', handleMessage);
     return () => {
       window.removeEventListener('message', handleMessage);
     };
@@ -178,17 +184,19 @@ export default function AuthModal({ isOpen, onClose }: AuthModalProps) {
           alignItems: 'center',
           width: '100%'
         }}>
-          <iframe
-            ref={iframeRef}
-            src={IframeReference.getIframeUrl()}
-            style={{
-              display: showIframe ? 'block' : 'none',
-              width: '400px',
-              height: '400px',
-              border: 'none',
-              overflow: 'hidden'
-            }}
-          />
+          {iframeSrc && (
+            <iframe
+              ref={iframeRef}
+              src={iframeSrc}
+              style={{
+                display: showIframe ? 'block' : 'none',
+                width: '400px',
+                height: '400px',
+                border: 'none',
+                overflow: 'hidden'
+              }}
+            />
+          )}
         </div>
       )}
     </Modal>
diff --git a/src/sdk/Iframe.tsx b/src/sdk/Iframe.tsx
index a2ac8afa..bdb1e0c5 100644
--- a/src/sdk/Iframe.tsx
+++ b/src/sdk/Iframe.tsx
@@ -1,4 +1,4 @@
-import { useRef, useEffect, memo } from 'react';
+import { useRef, useEffect, memo, useState } from 'react';
 import IframeReference from './IframeReference';
 
 interface IframeProps {
@@ -7,17 +7,30 @@ interface IframeProps {
 
 function Iframe({ showIframe = false }: IframeProps) {
   const iframeRef = useRef<HTMLIFrameElement>(null);
+  const [iframeSrc, setIframeSrc] = useState<string | null>(null);
 
   useEffect(() => {
+    // Client-side only: resolve iframe URL and set reference
+    try {
+      const url = IframeReference.getIframeUrl();
+      setIframeSrc(url);
+    } catch {
+      setIframeSrc(null);
+    }
     if (iframeRef.current) {
       IframeReference.setIframe(iframeRef.current);
     }
-  }, [iframeRef.current]);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
+  if (!iframeSrc) {
+    return null;
+  }
 
   return (
     <iframe
       ref={iframeRef}
-      src={IframeReference.getIframeUrl()}
+      src={iframeSrc}
       style={{
         display: showIframe ? 'block' : 'none',
         width: '400px',
diff --git a/src/sdk/MessageBus.ts b/src/sdk/MessageBus.ts
index f3ff7c67..f388dba8 100644
--- a/src/sdk/MessageBus.ts
+++ b/src/sdk/MessageBus.ts
@@ -22,10 +22,12 @@ export default class MessageBus {
   }
 
   public initMessageListener(): void {
+    if (typeof window === 'undefined') return;
     window.addEventListener('message', this.handleMessage.bind(this));
   }
 
   public destroyMessageListener(): void {
+    if (typeof window === 'undefined') return;
     window.removeEventListener('message', this.handleMessage.bind(this));
     this.isListening = false; // Reset the flag when destroying listener
   }
@@ -1003,7 +1005,9 @@ export default class MessageBus {
       try {
         const targetOrigin = IframeReference.getTargetOrigin();
         const iframe = IframeReference.getIframe();
-        iframe.contentWindow?.postMessage(message, targetOrigin);
+        if (typeof window !== 'undefined') {
+          iframe.contentWindow?.postMessage(message, targetOrigin);
+        }
         this.messagesSent.add(message.messageId);
       } catch (error) {
         console.error('[MessageBus] sendMessage: error', error);