diff --git a/apps/web/package.json b/apps/web/package.json
index 40216f64..ca80e54c 100644
--- a/apps/web/package.json
+++ b/apps/web/package.json
@@ -27,6 +27,7 @@
     "@uiw/react-codemirror": "^4.25.11",
     "ai": "7.0.58",
     "beautiful-mermaid": "^1.1.3",
+    "docx-preview": "0.4.1",
     "highlight.js": "^11.11.1",
     "html-to-image": "^1.11.13",
     "lowlight": "^3.3.0",
diff --git a/apps/web/src/components/attachments/DocxAttachmentPreview.tsx b/apps/web/src/components/attachments/DocxAttachmentPreview.tsx
new file mode 100644
index 00000000..103f5921
--- /dev/null
+++ b/apps/web/src/components/attachments/DocxAttachmentPreview.tsx
@@ -0,0 +1,69 @@
+import { Loader2 } from "lucide-react";
+import { useEffect, useState } from "react";
+import { useTranslation } from "react-i18next";
+import { buildDocxPreviewHtml } from "./docx-preview-html";
+import { DocxPreviewTooLargeError, loadDocxPreviewBytes } from "./docx-preview-source";
+
+type PreviewState =
+  | { status: "loading" }
+  | { status: "ready"; html: string }
+  | { status: "too-large" | "failed" };
+
+export const DocxAttachmentPreview = ({ url, filename }: { url: string; filename: string }) => {
+  const { t } = useTranslation();
+  const [state, setState] = useState<PreviewState>({ status: "loading" });
+
+  useEffect(() => {
+    const controller = new AbortController();
+    let active = true;
+    setState({ status: "loading" });
+
+    void loadDocxPreviewBytes(url, controller.signal)
+      .then(async (bytes) => {
+        if (!active) return;
+        const { renderAsync } = await import("docx-preview");
+        if (!active) return;
+        const body = document.createElement("div");
+        const styles = document.createElement("div");
+        await renderAsync(bytes, body, styles, {
+          renderAltChunks: false,
+          renderComments: false,
+          renderChanges: false,
+          useBase64URL: true,
+        });
+        body.querySelectorAll("a").forEach((link) => {
+          link.removeAttribute("href");
+          link.removeAttribute("target");
+          link.setAttribute("tabindex", "-1");
+        });
+        if (active) setState({ status: "ready", html: buildDocxPreviewHtml(styles.innerHTML, body.innerHTML) });
+      })
+      .catch((error: unknown) => {
+        if (!active) return;
+        setState({ status: error instanceof DocxPreviewTooLargeError ? "too-large" : "failed" });
+      });
+
+    return () => {
+      active = false;
+      controller.abort();
+    };
+  }, [url]);
+
+  if (state.status === "ready") {
+    return (
+      <iframe
+        aria-label={t("wordViewer.previewLabel", { filename })}
+        sandbox=""
+        srcDoc={state.html}
+        className="block h-[min(72vh,52rem)] w-full border-0 bg-slate-100"
+      />
+    );
+  }
+
+  return (
+    <span className="flex min-h-24 items-center justify-center gap-2 px-4 text-center text-sm text-slate-500" role="status">
+      {state.status === "loading" ? <Loader2 className="h-5 w-5 animate-spin" aria-hidden="true" /> : null}
+      {t(state.status === "loading" ? "wordViewer.loading" : state.status === "too-large" ? "wordViewer.previewTooLarge" : "wordViewer.unavailable")}
+    </span>
+  );
+};
diff --git a/apps/web/src/components/attachments/docx-preview-html.test.mjs b/apps/web/src/components/attachments/docx-preview-html.test.mjs
new file mode 100644
index 00000000..37c21109
--- /dev/null
+++ b/apps/web/src/components/attachments/docx-preview-html.test.mjs
@@ -0,0 +1,11 @@
+import { expect, test } from "bun:test";
+import { buildDocxPreviewHtml } from "./docx-preview-html.ts";
+
+test("keeps document styling inside a restricted preview document", () => {
+  const html = buildDocxPreviewHtml("<style>.docx { color: red }</style>", "<p>Draft</p>");
+  expect(html).toContain("default-src 'none'");
+  expect(html).toContain("script-src 'none'");
+  expect(html).toContain("connect-src 'none'");
+  expect(html).toContain("img-src data:");
+  expect(html).toContain("<p>Draft</p>");
+});
diff --git a/apps/web/src/components/attachments/docx-preview-html.ts b/apps/web/src/components/attachments/docx-preview-html.ts
new file mode 100644
index 00000000..99cf6fe9
--- /dev/null
+++ b/apps/web/src/components/attachments/docx-preview-html.ts
@@ -0,0 +1,8 @@
+const PREVIEW_CSP = "default-src 'none'; script-src 'none'; connect-src 'none'; img-src data:; font-src data:; style-src 'unsafe-inline'; frame-src 'none'; object-src 'none'; base-uri 'none'; form-action 'none'";
+
+/** The iframe also has an empty sandbox: document markup cannot run scripts or navigate its parent. */
+export const buildDocxPreviewHtml = (styles: string, body: string) => `<!doctype html>
+<html><head><meta charset="utf-8"><meta http-equiv="Content-Security-Policy" content="${PREVIEW_CSP}">
+${styles}
+<style>html,body{margin:0;min-height:100%;background:#f1f5f9}a{pointer-events:none!important}</style>
+</head><body>${body}</body></html>`;
diff --git a/apps/web/src/components/attachments/docx-preview-source.test.mjs b/apps/web/src/components/attachments/docx-preview-source.test.mjs
new file mode 100644
index 00000000..5107e1ca
--- /dev/null
+++ b/apps/web/src/components/attachments/docx-preview-source.test.mjs
@@ -0,0 +1,62 @@
+import { afterEach, describe, expect, test } from "bun:test";
+import {
+  DocxPreviewTooLargeError,
+  isPreviewableDocx,
+  loadDocxPreviewBytes,
+  MAX_INLINE_DOCX_BYTES,
+} from "./docx-preview-source.ts";
+
+const originalFetch = globalThis.fetch;
+afterEach(() => { globalThis.fetch = originalFetch; });
+
+describe("DOCX preview source", () => {
+  test("only offers inline preview for note-owned DOCX resources", () => {
+    expect(isPreviewableDocx("Report.DOCX", "/api/v1/resources/res_1/blob")).toBe(true);
+    expect(isPreviewableDocx("draft.docx", "edgeever-staged://stage_1")).toBe(true);
+    expect(isPreviewableDocx("old.doc", "/api/v1/resources/res_1/blob")).toBe(false);
+    expect(isPreviewableDocx("report.docx", "https://other.example/report.docx")).toBe(false);
+  });
+
+  test("reads staged desktop bytes without mutating the bridge buffer", async () => {
+    const original = new Uint8Array([1, 2, 3]);
+    const bridge = {
+      readResource: async () => { throw new Error("wrong source"); },
+      readStagedResource: async (id) => {
+        expect(id).toBe("stage_1");
+        return { bytes: original };
+      },
+    };
+    const bytes = await loadDocxPreviewBytes("edgeever-staged://stage_1", undefined, bridge);
+    expect(bytes).toEqual(original);
+    expect(bytes).not.toBe(original);
+  });
+
+  test("rejects a declared oversized resource before reading its body", async () => {
+    globalThis.fetch = async () => new Response("", {
+      headers: { "Content-Length": String(MAX_INLINE_DOCX_BYTES + 1) },
+    });
+    await expect(loadDocxPreviewBytes("/api/v1/resources/res_1/blob", undefined, undefined))
+      .rejects.toBeInstanceOf(DocxPreviewTooLargeError);
+  });
+
+  test("stops an oversized stream even without Content-Length", async () => {
+    globalThis.fetch = async () => new Response(new ReadableStream({
+      start(controller) {
+        controller.enqueue(new Uint8Array(MAX_INLINE_DOCX_BYTES));
+        controller.enqueue(new Uint8Array([1]));
+        controller.close();
+      },
+    }));
+    await expect(loadDocxPreviewBytes("/api/v1/resources/res_1/blob", undefined, undefined))
+      .rejects.toBeInstanceOf(DocxPreviewTooLargeError);
+  });
+
+  test("loads a small authenticated resource", async () => {
+    globalThis.fetch = async (_url, options) => {
+      expect(options.credentials).toBe("same-origin");
+      return new Response(new Uint8Array([4, 5, 6]));
+    };
+    await expect(loadDocxPreviewBytes("/api/v1/resources/res_1/blob", undefined, undefined))
+      .resolves.toEqual(new Uint8Array([4, 5, 6]));
+  });
+});
diff --git a/apps/web/src/components/attachments/docx-preview-source.ts b/apps/web/src/components/attachments/docx-preview-source.ts
new file mode 100644
index 00000000..60cad840
--- /dev/null
+++ b/apps/web/src/components/attachments/docx-preview-source.ts
@@ -0,0 +1,84 @@
+import { normalizeAttachmentByteSize } from "@edgeever/shared";
+
+export const MAX_INLINE_DOCX_BYTES = 10 * 1024 * 1024;
+
+export class DocxPreviewTooLargeError extends Error {}
+
+export const isPreviewableDocx = (filename: string, url: string) =>
+  /\.docx$/i.test(filename.trim())
+  && (url.startsWith("/api/v1/resources/")
+    || url.startsWith("edgeever-resource://")
+    || url.startsWith("edgeever-staged://"));
+
+const desktopResourceId = (url: string, scheme: "edgeever-resource:" | "edgeever-staged:") => {
+  try {
+    const parsed = new URL(url);
+    if (parsed.protocol !== scheme) return null;
+    const id = parsed.pathname.replace(/^\//, "") || parsed.hostname;
+    return id ? decodeURIComponent(id) : null;
+  } catch {
+    return null;
+  }
+};
+
+const requireAllowedSize = (size: number) => {
+  if (size > MAX_INLINE_DOCX_BYTES) throw new DocxPreviewTooLargeError();
+};
+
+export const loadDocxPreviewBytes = async (
+  url: string,
+  signal?: AbortSignal,
+  bridge: Pick<EdgeEverDesktopBridge, "readResource" | "readStagedResource"> | undefined =
+    typeof window === "undefined" ? undefined : window.edgeeverDesktop,
+): Promise<Uint8Array> => {
+  const stagedId = desktopResourceId(url, "edgeever-staged:");
+  const resourceId = desktopResourceId(url, "edgeever-resource:");
+  if (bridge && (stagedId || resourceId)) {
+    const resource = stagedId
+      ? await bridge.readStagedResource(stagedId)
+      : await bridge.readResource(resourceId!);
+    requireAllowedSize(resource.bytes.byteLength);
+    return new Uint8Array(resource.bytes);
+  }
+
+  if (!url.startsWith("/api/v1/resources/")) throw new Error("Unsupported DOCX resource URL");
+  const response = await fetch(url, { credentials: "same-origin", cache: "no-store", signal });
+  if (!response.ok) throw new Error(`DOCX resource request failed: ${response.status}`);
+  const declaredSize = normalizeAttachmentByteSize(response.headers.get("Content-Length"));
+  if (declaredSize !== null && declaredSize > MAX_INLINE_DOCX_BYTES) {
+    await response.body?.cancel().catch(() => undefined);
+    throw new DocxPreviewTooLargeError();
+  }
+
+  if (!response.body) {
+    const bytes = new Uint8Array(await response.arrayBuffer());
+    requireAllowedSize(bytes.byteLength);
+    return bytes;
+  }
+
+  const reader = response.body.getReader();
+  const chunks: Uint8Array[] = [];
+  let byteLength = 0;
+  try {
+    while (true) {
+      const { done, value } = await reader.read();
+      if (done) break;
+      byteLength += value.byteLength;
+      requireAllowedSize(byteLength);
+      chunks.push(value);
+    }
+  } catch (error) {
+    await reader.cancel().catch(() => undefined);
+    throw error;
+  } finally {
+    reader.releaseLock();
+  }
+
+  const bytes = new Uint8Array(byteLength);
+  let offset = 0;
+  for (const chunk of chunks) {
+    bytes.set(chunk, offset);
+    offset += chunk.byteLength;
+  }
+  return bytes;
+};
diff --git a/apps/web/src/components/editor/FileAttachment.tsx b/apps/web/src/components/editor/FileAttachment.tsx
index f6be7f39..a931ea7b 100644
--- a/apps/web/src/components/editor/FileAttachment.tsx
+++ b/apps/web/src/components/editor/FileAttachment.tsx
@@ -11,7 +11,9 @@ import { ChevronDown, ChevronUp, Download, ExternalLink } from "lucide-react";
 import { useTranslation } from "react-i18next";
 import { AttachmentFileIcon } from "@/components/attachments/AttachmentFileIcon";
 import { AudioAttachmentPlayer } from "@/components/attachments/AudioAttachmentPlayer";
+import { DocxAttachmentPreview } from "@/components/attachments/DocxAttachmentPreview";
 import { COMPACT_ATTACHMENT_WIDTH_CLASS } from "@/components/attachments/attachment-layout";
+import { isPreviewableDocx, MAX_INLINE_DOCX_BYTES } from "@/components/attachments/docx-preview-source";
 import { VideoAttachmentPlayer } from "@/components/attachments/VideoAttachmentPlayer";
 import { ButtonTooltip } from "@/components/ui/button-tooltip";
 import { useAttachmentByteSize } from "@/hooks/useAttachmentByteSize";
@@ -23,6 +25,7 @@ import { AttachmentTranscriptInline } from "./AttachmentTranscriptInline";
 const FileAttachmentNodeView = ({ node, updateAttributes }: NodeViewProps) => {
   const { t } = useTranslation();
   const [viewerElement, setViewerElement] = useState<HTMLSpanElement | null>(null);
+  const [docxExpanded, setDocxExpanded] = useState(false);
   const transcriptContext = useContext(AttachmentTranscriptContext);
   const activeTranscript = transcriptContext?.transcript?.target.element
     && viewerElement?.contains(transcriptContext.transcript.target.element)
@@ -40,17 +43,24 @@ const FileAttachmentNodeView = ({ node, updateAttributes }: NodeViewProps) => {
   const attachmentKind = resolveAttachmentKind(mimeType, filename || label);
   const isAudio = attachmentKind === "audio";
   const isVideo = attachmentKind === "video";
+  const isDocx = isPreviewableDocx(filename || label, resolvedUrl);
+  const docxPreviewAllowed = isDocx && (byteSize === null || byteSize <= MAX_INLINE_DOCX_BYTES);
   const videoExpanded = isVideo && resolveFileDisplayMode(node.attrs.displayMode) === "inline";
+  const expandable = isVideo || docxPreviewAllowed;
+  const expanded = isVideo ? videoExpanded : docxExpanded;
   const setVideoExpanded = (expanded: boolean) => {
     updateAttributes({ displayMode: expanded ? "inline" : "compact" });
   };
+  const toggleExpanded = () => isVideo ? setVideoExpanded(!videoExpanded) : setDocxExpanded(!docxExpanded);
 
   const identity = (
     <>
       <AttachmentFileIcon mimeType={mimeType} filename={filename || label} className="h-5 w-5 shrink-0" />
       <span className="flex min-w-0 flex-col">
         <span className="truncate text-sm font-semibold text-slate-800">{label}</span>
-        <span className="truncate text-xs font-medium text-slate-500">{metadata}</span>
+        <span className="truncate text-xs font-medium text-slate-500">
+          {isDocx && !docxPreviewAllowed ? `${metadata} · ${t("wordViewer.previewTooLarge")}` : metadata}
+        </span>
       </span>
     </>
   );
@@ -65,12 +75,12 @@ const FileAttachmentNodeView = ({ node, updateAttributes }: NodeViewProps) => {
     >
       <span ref={setViewerElement} className={cn("edgeever-file-viewer flex min-h-12 flex-col overflow-hidden rounded-xl border border-slate-200 bg-card shadow-sm", COMPACT_ATTACHMENT_WIDTH_CLASS)}>
         <span data-edgeever-resource-toolbar className="flex min-h-12 items-center gap-2 px-3">
-          {isVideo ? (
+          {expandable ? (
             <button
               type="button"
               className="flex min-w-0 flex-1 cursor-pointer items-center gap-2 text-left"
-              aria-expanded={videoExpanded}
-              onClick={() => setVideoExpanded(!videoExpanded)}
+              aria-expanded={expanded}
+              onClick={toggleExpanded}
             >
               {identity}
             </button>
@@ -94,16 +104,16 @@ const FileAttachmentNodeView = ({ node, updateAttributes }: NodeViewProps) => {
               <ExternalLink aria-hidden="true" />
             </a>
           </ButtonTooltip>
-          {isVideo ? (
-            <ButtonTooltip title={videoExpanded ? t("pdfViewer.collapse") : t("pdfViewer.expand")}>
+          {expandable ? (
+            <ButtonTooltip title={expanded ? t("pdfViewer.collapse") : t("pdfViewer.expand")}>
               <button
                 type="button"
                 className="pdf-viewer-action"
-                aria-label={videoExpanded ? t("pdfViewer.collapse") : t("pdfViewer.expand")}
-                aria-expanded={videoExpanded}
-                onClick={() => setVideoExpanded(!videoExpanded)}
+                aria-label={expanded ? t("pdfViewer.collapse") : t("pdfViewer.expand")}
+                aria-expanded={expanded}
+                onClick={toggleExpanded}
               >
-                {videoExpanded ? <ChevronUp aria-hidden="true" /> : <ChevronDown aria-hidden="true" />}
+                {expanded ? <ChevronUp aria-hidden="true" /> : <ChevronDown aria-hidden="true" />}
               </button>
             </ButtonTooltip>
           ) : null}
@@ -128,6 +138,11 @@ const FileAttachmentNodeView = ({ node, updateAttributes }: NodeViewProps) => {
             />
           </span>
         ) : null}
+        {docxPreviewAllowed && docxExpanded && resolvedUrl ? (
+          <span className="border-t border-slate-200">
+            <DocxAttachmentPreview url={resolvedUrl} filename={filename || label} />
+          </span>
+        ) : null}
       </span>
       {activeTranscript && transcriptContext ? (
         <span className={cn("block", COMPACT_ATTACHMENT_WIDTH_CLASS)}>
diff --git a/bun.lock b/bun.lock
index 5fa3fe60..713f22d5 100644
--- a/bun.lock
+++ b/bun.lock
@@ -245,6 +245,7 @@
         "@uiw/react-codemirror": "^4.25.11",
         "ai": "7.0.58",
         "beautiful-mermaid": "^1.1.3",
+        "docx-preview": "0.4.1",
         "highlight.js": "^11.11.1",
         "html-to-image": "^1.11.13",
         "lowlight": "^3.3.0",
@@ -2258,6 +2259,8 @@
 
     "dnssd-advertise": ["dnssd-advertise@1.1.6", "", {}, "sha512-Ndrrf6BMPalkQPd/zubL+4YghH2J9NspapQ09uDXwYbvOPkP0oaqf5CkcwJ0b50kS2O3ul6yVu+jz+RY62Cejg=="],
 
+    "docx-preview": ["docx-preview@0.4.1", "", { "dependencies": { "jszip": ">=3.0.0" } }, "sha512-Dv4g+LeE0swHpPvNC0lAT0YsR5Zq5pAxw7d3vHQ8EChBLgIrqqe9VPL5nVt2HBJap8bEZbXUI0TJob7kBeNU9w=="],
+
     "dom-align": ["dom-align@1.12.4", "", {}, "sha512-R8LUSEay/68zE5c8/3BDxiTEvgb4xZTF0RKmAHfiEVN3klfIpXfi2/QCoiWPccVQ0J/ZGdz9OjzL4uJEP/MRAw=="],
 
     "dom-serializer": ["dom-serializer@2.0.0", "", { "dependencies": { "domelementtype": "^2.3.0", "domhandler": "^5.0.2", "entities": "^4.2.0" } }, "sha512-wIkAryiqt/nV5EQKqQpo3SToSOV9J0DnbJqwK7Wv/Trc92zIAYZ4FlMu+JPFW1DfGFt81ZTCGgDEabffXeLyJg=="],
diff --git a/packages/shared/src/i18n/en-US.ts b/packages/shared/src/i18n/en-US.ts
index e1bc87ff..e6e250a8 100644
--- a/packages/shared/src/i18n/en-US.ts
+++ b/packages/shared/src/i18n/en-US.ts
@@ -2015,6 +2015,12 @@ export const enUS = {
     previous: "Previous PDF",
     next: "Next PDF",
   },
+  wordViewer: {
+    loading: "Loading Word preview…",
+    unavailable: "This Word document cannot be previewed. You can still download it or open it externally.",
+    previewTooLarge: "Preview disabled over 10 MiB",
+    previewLabel: "Word preview: {{filename}}",
+  },
   audioPlayer: {
     label: "Audio player: {{filename}}",
     unavailable: "This audio format cannot be played on this device. You can still download it or open it externally.",
diff --git a/packages/shared/src/i18n/ja.ts b/packages/shared/src/i18n/ja.ts
index 90fad7e3..89022afb 100644
--- a/packages/shared/src/i18n/ja.ts
+++ b/packages/shared/src/i18n/ja.ts
@@ -2015,6 +2015,12 @@ export const ja = {
     previous: "前の PDF",
     next: "次の PDF",
   },
+  wordViewer: {
+    loading: "Word のプレビューを読み込み中…",
+    unavailable: "この Word 文書はプレビューできません。ダウンロードするか、外部で開くことはできます。",
+    previewTooLarge: "10 MiB 超のためプレビューしません",
+    previewLabel: "Word プレビュー：{{filename}}",
+  },
   audioPlayer: {
     label: "音声プレーヤー：{{filename}}",
     unavailable: "この端末ではこの音声形式を再生できません。ダウンロードするか、外部で開くことはできます。",
diff --git a/packages/shared/src/i18n/pl.ts b/packages/shared/src/i18n/pl.ts
index 1ebab822..403e2077 100644
--- a/packages/shared/src/i18n/pl.ts
+++ b/packages/shared/src/i18n/pl.ts
@@ -2015,6 +2015,12 @@ export const pl = {
     previous: "Poprzedni PDF",
     next: "Następny PDF",
   },
+  wordViewer: {
+    loading: "Wczytywanie podglądu Word…",
+    unavailable: "Nie można wyświetlić podglądu tego dokumentu Word. Nadal możesz go pobrać lub otworzyć w innej aplikacji.",
+    previewTooLarge: "Podgląd wyłączony powyżej 10 MiB",
+    previewLabel: "Podgląd Word: {{filename}}",
+  },
   audioPlayer: {
     label: "Odtwarzacz audio: {{filename}}",
     unavailable: "Tego formatu audio nie można odtworzyć na tym urządzeniu. Nadal możesz go pobrać lub otworzyć w innej aplikacji.",
diff --git a/packages/shared/src/i18n/zh-CN.ts b/packages/shared/src/i18n/zh-CN.ts
index 1ccd3f96..a683bbe9 100644
--- a/packages/shared/src/i18n/zh-CN.ts
+++ b/packages/shared/src/i18n/zh-CN.ts
@@ -2015,6 +2015,12 @@ export const zhCN = {
     previous: "上一个 PDF",
     next: "下一个 PDF",
   },
+  wordViewer: {
+    loading: "正在加载 Word 预览…",
+    unavailable: "无法预览此 Word 文档，你仍可下载或在外部打开。",
+    previewTooLarge: "超过 10 MiB，不在笔记内预览",
+    previewLabel: "Word 预览：{{filename}}",
+  },
   audioPlayer: {
     label: "音频播放器：{{filename}}",
     unavailable: "当前设备无法播放此音频格式，你仍可下载或在外部打开。",