diff --git a/apps/cs/app/api/proxy/[...url]/route.ts b/apps/cs/app/api/proxy/[...url]/route.ts
index 0929ca57c..4385956d3 100644
--- a/apps/cs/app/api/proxy/[...url]/route.ts
+++ b/apps/cs/app/api/proxy/[...url]/route.ts
@@ -1,3 +1,6 @@
+import { cookies } from "next/headers";
+import { NextResponse } from "next/server";
+
 import {
   ACCESS_TOKEN,
   AUTH_USER_ID,
@@ -7,8 +10,6 @@ import {
   SERVER_API_URL,
   SITE_ID,
 } from "@/shared/config";
-import { cookies } from "next/headers";
-import { NextResponse } from "next/server";
 
 async function handler(
   request: Request,
@@ -20,6 +21,10 @@ async function handler(
     "Content-Type": "application/json",
     "X-Site-Id": SITE_ID,
   };
+  const deviceId = request.headers.get("X-Device-Id");
+  if (deviceId) {
+    headers["X-Device-Id"] = deviceId;
+  }
   let body = {};
   const isRefreshHandler = params.url.includes("refresh");
 
diff --git a/apps/cs/package.json b/apps/cs/package.json
index d362d1178..710032627 100644
--- a/apps/cs/package.json
+++ b/apps/cs/package.json
@@ -45,6 +45,7 @@
     "sonner": "^2.0.1",
     "tailwindcss-animate": "^1.0.7",
     "tus-js-client": "^4.3.1",
+    "uuid": "^14.0.1",
     "zod": "^3.24.2",
     "zustand": "^5.0.3"
   },
diff --git a/apps/cs/src/entities/auth/api/auth-service.ts b/apps/cs/src/entities/auth/api/auth-service.ts
index 3efb1bf85..a8312e46c 100644
--- a/apps/cs/src/entities/auth/api/auth-service.ts
+++ b/apps/cs/src/entities/auth/api/auth-service.ts
@@ -10,6 +10,7 @@ import {
   getRemainingMs,
 } from "@common/auth";
 
+import { clearDeviceId, getOrCreateDeviceId } from "../lib/device-id";
 import {
   clearRefreshTimer,
   removeToken,
@@ -36,7 +37,10 @@ function resolveLoginError(message: string | undefined): string {
 async function login(payload: AuthPayload): Promise<void> {
   const response = await fetch(`/api/proxy${ENDPOINT.USER_SERVICE.LOGIN}`, {
     method: "POST",
-    headers: { "Content-Type": "application/json" },
+    headers: {
+      "Content-Type": "application/json",
+      "X-Device-Id": getOrCreateDeviceId(),
+    },
     body: JSON.stringify(payload),
   });
 
@@ -67,7 +71,12 @@ async function silentRefresh(): Promise<void> {
   try {
     const response = await fetch(
       `/api/proxy${ENDPOINT.USER_SERVICE.SILENT_REFRESH}`,
-      { method: "PUT" },
+      {
+        method: "PUT",
+        headers: {
+          "X-Device-Id": getOrCreateDeviceId(),
+        },
+      },
     );
 
     const data = await response.json();
@@ -105,6 +114,7 @@ async function silentRefresh(): Promise<void> {
 
 async function logout(): Promise<void> {
   tokenManager.clearAuthToken();
+  clearDeviceId();
   removeToken("site-id-key");
   removeToken("site-theme-key");
 
diff --git a/apps/cs/src/entities/auth/lib/device-id.ts b/apps/cs/src/entities/auth/lib/device-id.ts
new file mode 100644
index 000000000..3683c7189
--- /dev/null
+++ b/apps/cs/src/entities/auth/lib/device-id.ts
@@ -0,0 +1,20 @@
+import { v4 as uuidv4 } from "uuid";
+
+const DEVICE_ID_KEY = "x-device-id";
+
+export function getOrCreateDeviceId(): string {
+  if (typeof window === "undefined") return "";
+
+  const existing = localStorage.getItem(DEVICE_ID_KEY);
+  if (existing) return existing;
+
+  const id = uuidv4();
+  localStorage.setItem(DEVICE_ID_KEY, id);
+  return id;
+}
+
+export function clearDeviceId(): void {
+  if (typeof window === "undefined") return;
+
+  localStorage.removeItem(DEVICE_ID_KEY);
+}