diff --git a/src/client.ts b/src/client.ts
index 84bfc15a..6ea54adc 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -8,6 +8,7 @@ import {
   createUserConnectorsModule,
 } from "./modules/connectors.js";
 import { getAccessToken } from "./utils/auth-utils.js";
+import { createFetchWithAuth } from "./utils/fetch-with-auth.js";
 import { createFunctionsModule } from "./modules/functions.js";
 import { createAgentsModule } from "./modules/agents.js";
 import { createAiGatewayModule } from "./modules/ai-gateway.js";
@@ -323,6 +324,9 @@ export function createClient(config: CreateClientConfig): Base44Client {
   const client = {
     ...userModules,
 
+    /** See {@link Base44Client.fetchWithAuth}. */
+    fetchWithAuth: createFetchWithAuth(axiosClient),
+
     /**
      * Sets a new authentication token for all subsequent requests.
      *
diff --git a/src/client.types.ts b/src/client.types.ts
index b94a6333..3d36018c 100644
--- a/src/client.types.ts
+++ b/src/client.types.ts
@@ -147,6 +147,45 @@ export interface Base44Client {
   /** Cleanup function to disconnect WebSocket connections. Call when you're done with the client. */
   cleanup: () => void;
 
+  /**
+   * Calls one of your app's own server routes with the signed-in user's access token attached.
+   *
+   * Base44 keeps the user's access token in the browser's local storage, so a plain `fetch()` to your app's server routes arrives without it and the route sees an anonymous caller. `fetchWithAuth()` is the same `fetch()` with the `Authorization: Bearer <token>` header added, which is what lets a server route act on behalf of the signed-in user.
+   *
+   * Requests are restricted to your app's own origin so the token is never sent to a third party: pass a relative path beginning with a single `/`, such as `/api/orders`. An absolute URL, a protocol-relative `//host`, or anything else that a URL parser would read as another origin throws. To call a Base44 backend function, use {@linkcode FunctionsModule.fetch | functions.fetch()}; for another origin, use plain `fetch()`.
+   *
+   * The path is passed to `fetch` unchanged, so this also works in server code, where the runtime's `fetch` decides what a relative path means — a server-side client from {@linkcode createClientFromRequest | createClientFromRequest()} carries the caller's own token. Note that only the `Authorization` header is added: a route that builds its own client from the incoming request also needs the platform's `Base44-App-Id` and `Base44-Api-Url`, which a request you construct yourself does not have.
+   *
+   * When no user is signed in the request is sent without an `Authorization` header, so routes that allow anonymous access keep working.
+   *
+   * @param path - A relative path on your app's own origin, such as `/api/orders`.
+   * @param init - Optional [`RequestInit`](https://developer.mozilla.org/en-US/docs/Web/API/RequestInit) options such as `method`, `headers`, `body`, and `signal`. The auth header is added automatically; an `Authorization` header you set yourself is kept.
+   * @returns Promise resolving to a native [`Response`](https://developer.mozilla.org/en-US/docs/Web/API/Response).
+   * @throws {Error} When `path` is not a relative path on your app's own origin.
+   *
+   * @example
+   * ```typescript
+   * // Call your app's own server route as the signed-in user
+   * const response = await base44.fetchWithAuth('/api/orders');
+   * const orders = await response.json();
+   * ```
+   *
+   * @example
+   * ```typescript
+   * // POST with a JSON body
+   * const response = await base44.fetchWithAuth('/api/orders', {
+   *   method: 'POST',
+   *   headers: { 'Content-Type': 'application/json' },
+   *   body: JSON.stringify({ productId: 'abc', quantity: 2 }),
+   * });
+   *
+   * if (!response.ok) {
+   *   throw new Error(`Request failed: ${response.status}`);
+   * }
+   * ```
+   */
+  fetchWithAuth(path: string, init?: RequestInit): Promise<Response>;
+
   /**
    * Sets a new authentication token for all subsequent requests.
    *
diff --git a/src/utils/fetch-with-auth.ts b/src/utils/fetch-with-auth.ts
new file mode 100644
index 00000000..73c44be9
--- /dev/null
+++ b/src/utils/fetch-with-auth.ts
@@ -0,0 +1,65 @@
+import type { AxiosInstance } from "axios";
+
+/**
+ * Builds the client's `fetchWithAuth`: a `fetch` that attaches the signed-in
+ * user's access token to a request for the app's own origin.
+ *
+ * @param axios - The user-scoped axios instance. Its `Authorization` default is
+ * the live token: it follows `setToken()` and is deleted on `logout()`, so a
+ * request never carries a token the user no longer has. In a server-side client
+ * from `createClientFromRequest()` it holds the caller's own token.
+ * @internal
+ */
+export function createFetchWithAuth(axios: AxiosInstance) {
+  const currentToken = (): string | null => {
+    const header = axios.defaults.headers.common["Authorization"];
+    if (typeof header !== "string" || !header.startsWith("Bearer ")) {
+      return null;
+    }
+    return header.slice("Bearer ".length) || null;
+  };
+
+  return async function fetchWithAuth(
+    path: string,
+    init: RequestInit = {}
+  ): Promise<Response> {
+    assertOwnOriginPath(path);
+
+    const headers = new Headers(init.headers);
+    const token = currentToken();
+
+    if (token && !headers.has("Authorization")) {
+      headers.set("Authorization", `Bearer ${token}`);
+    }
+
+    // Passed through untouched: resolving it here would need a document, and a
+    // root-relative path is already what a runtime that dispatches in-process
+    // (Nitro's `fetch`) expects.
+    return fetch(path, { ...init, headers });
+  };
+}
+
+function assertOwnOriginPath(path: string): void {
+  if (typeof path !== "string" || path === "") {
+    throw new Error("fetchWithAuth() requires a path, such as '/api/orders'.");
+  }
+
+  // Check what a URL parser would see, not the raw string: it drops every ASCII
+  // tab/newline anywhere in the input and trims leading C0/space, so
+  // "/<tab>/evil.example" would pass a naive prefix check and then resolve to
+  // another host.
+  const asParsed = path.replace(/[\t\n\r]/g, "").replace(/^[\x00-\x20]+/, "");
+
+  // One leading slash is the whole rule: it cannot carry a scheme, and it rules
+  // out the two forms that reach another origin — "//host" and, since URL
+  // parsing treats a backslash as a slash, "/\host".
+  if (
+    !asParsed.startsWith("/") ||
+    asParsed.startsWith("//") ||
+    asParsed.startsWith("/\\")
+  ) {
+    throw new Error(
+      `fetchWithAuth() only sends requests to your app's own origin, so the access token never reaches a third party. "${path}" is not a path on it — pass a relative path such as '/api/orders'. Use base44.functions.fetch() to call a Base44 backend function, or plain fetch() for another origin.`
+    );
+  }
+}
diff --git a/tests/unit/fetch-with-auth.test.ts b/tests/unit/fetch-with-auth.test.ts
new file mode 100644
index 00000000..7534b843
--- /dev/null
+++ b/tests/unit/fetch-with-auth.test.ts
@@ -0,0 +1,193 @@
+import { afterEach, beforeEach, describe, expect, test, vi } from "vitest";
+import { createClient } from "../../src/index.ts";
+
+const appId = "test-app-id";
+const origin = "https://my-app.base44.app";
+
+function makeLocalStorage(initial: Record<string, string> = {}) {
+  const store = new Map<string, string>(Object.entries(initial));
+  return {
+    getItem: (k: string) => (store.has(k) ? store.get(k)! : null),
+    setItem: (k: string, v: string) => {
+      store.set(k, v);
+    },
+    removeItem: (k: string) => {
+      store.delete(k);
+    },
+    clear: () => store.clear(),
+  };
+}
+
+function stubBrowser(storage = makeLocalStorage()) {
+  vi.stubGlobal("document", { referrer: "", visibilityState: "visible" });
+  vi.stubGlobal("window", {
+    addEventListener: vi.fn(),
+    removeEventListener: vi.fn(),
+    history: { replaceState: vi.fn() },
+    location: {
+      href: `${origin}/dashboard`,
+      origin,
+      pathname: "/dashboard",
+      search: "",
+    },
+    localStorage: storage,
+  });
+  vi.stubGlobal("localStorage", storage);
+}
+
+const createTestClient = (token?: string) =>
+  createClient({
+    serverUrl: "",
+    appId,
+    token,
+    analytics: { enabled: false },
+  });
+
+let fetchMock: ReturnType<typeof vi.fn>;
+
+beforeEach(() => {
+  fetchMock = vi.fn().mockResolvedValue(new Response("{}"));
+  vi.stubGlobal("fetch", fetchMock);
+});
+
+afterEach(() => {
+  vi.unstubAllGlobals();
+  vi.clearAllMocks();
+});
+
+const lastCall = () => {
+  const [url, init] = fetchMock.mock.calls[0];
+  return { url, init, headers: new Headers(init.headers) };
+};
+
+describe("fetchWithAuth", () => {
+  test("attaches the user's token to a same-origin path", async () => {
+    stubBrowser();
+    const base44 = createTestClient("user-token");
+
+    await base44.fetchWithAuth("/api/orders");
+
+    const { url, headers } = lastCall();
+    expect(url).toBe("/api/orders");
+    expect(headers.get("Authorization")).toBe("Bearer user-token");
+  });
+
+  test("reads the token from local storage when the client was created without one", async () => {
+    stubBrowser(makeLocalStorage({ base44_access_token: "stored-token" }));
+    const base44 = createTestClient();
+
+    await base44.fetchWithAuth("/api/orders");
+
+    expect(lastCall().headers.get("Authorization")).toBe("Bearer stored-token");
+  });
+
+  test("uses the token set after login", async () => {
+    stubBrowser();
+    const base44 = createTestClient("old-token");
+
+    base44.setToken("new-token");
+    await base44.fetchWithAuth("/api/orders");
+
+    expect(lastCall().headers.get("Authorization")).toBe("Bearer new-token");
+  });
+
+  test("sends no auth header after logout", async () => {
+    stubBrowser();
+    const base44 = createTestClient("user-token");
+
+    base44.auth.logout();
+    // logout() navigates the page; the test keeps the stubbed location usable.
+    (globalThis as any).window.location.href = `${origin}/dashboard`;
+    await base44.fetchWithAuth("/api/orders");
+
+    expect(lastCall().headers.get("Authorization")).toBeNull();
+  });
+
+  test("sends no auth header when no user is signed in", async () => {
+    stubBrowser();
+    const base44 = createTestClient();
+
+    await base44.fetchWithAuth("/api/public");
+
+    expect(lastCall().headers.get("Authorization")).toBeNull();
+    expect(fetchMock).toHaveBeenCalledTimes(1);
+  });
+
+  test("forwards init options and keeps a caller-set Authorization header", async () => {
+    stubBrowser();
+    const base44 = createTestClient("user-token");
+
+    await base44.fetchWithAuth("/api/orders", {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+        Authorization: "Bearer caller-token",
+      },
+      body: JSON.stringify({ productId: "abc" }),
+    });
+
+    const { init, headers } = lastCall();
+    expect(init.method).toBe("POST");
+    expect(init.body).toBe(JSON.stringify({ productId: "abc" }));
+    expect(headers.get("Content-Type")).toBe("application/json");
+    expect(headers.get("Authorization")).toBe("Bearer caller-token");
+  });
+
+  test("passes the path through untouched", async () => {
+    stubBrowser();
+    const base44 = createTestClient("user-token");
+
+    await base44.fetchWithAuth("/api/orders?status=open#top");
+
+    expect(lastCall().url).toBe("/api/orders?status=open#top");
+  });
+
+  test.each([
+    ["an absolute URL", "https://evil.example/steal"],
+    ["a protocol-relative path", "//evil.example/steal"],
+    ["a backslash-prefixed path", "/\\evil.example/steal"],
+    ["an absolute URL on another port", `${origin}:8443/api/orders`],
+    ["a bare relative path", "api/orders"],
+    // A URL parser drops tabs/newlines and trims leading space, so these read
+    // as "//evil.example" by the time the request is built.
+    ["a tab-split protocol-relative path", "/\t/evil.example/steal"],
+    ["a newline-split protocol-relative path", "/\n/evil.example/steal"],
+    ["a space-padded protocol-relative path", "  //evil.example/steal"],
+  ])("rejects %s", async (_label, path) => {
+    stubBrowser();
+    const base44 = createTestClient("user-token");
+
+    await expect(base44.fetchWithAuth(path)).rejects.toThrow(
+      /only sends requests to your app's own origin/
+    );
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
+
+  test("rejects an empty path", async () => {
+    stubBrowser();
+    const base44 = createTestClient("user-token");
+
+    await expect(base44.fetchWithAuth("")).rejects.toThrow(/requires a path/);
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
+
+  test("works with no document, as in a server route", async () => {
+    // No stubBrowser(): window is undefined here, the way it is on a worker.
+    const base44 = createTestClient("caller-token");
+
+    await base44.fetchWithAuth("/api/orders");
+
+    const { url, headers } = lastCall();
+    expect(url).toBe("/api/orders");
+    expect(headers.get("Authorization")).toBe("Bearer caller-token");
+  });
+
+  test("rejects another origin with no document too", async () => {
+    const base44 = createTestClient("caller-token");
+
+    await expect(
+      base44.fetchWithAuth("https://evil.example/steal")
+    ).rejects.toThrow(/only sends requests to your app's own origin/);
+    expect(fetchMock).not.toHaveBeenCalled();
+  });
+});