This entire codebase — Rust parsers, TypeScript renderers, tests, and tooling — is implemented by AI coding agents, primarily Claude and Codex, through iterative prompting. No human-written application code exists in this repository.

Why this project exists — a note from the author

OOXML's behavior is defined by a written specification (ECMA-376 / ISO-29500), and there is a clear answer to compare against: Word, Excel, and PowerPoint themselves. In principle, anyone with enough patience could have built a faithful viewer — the spec says what to implement, and the Office applications show whether you got it right.

In practice, it didn't happen. For more than a decade, no free, open-source library reached a rendering quality good enough for real use. There are a few commercial libraries with decent fidelity (and editing support), but their pricing makes them hard to adopt casually. I think the reason is simply cost: the specification is huge, and reading and implementing it faithfully takes far more effort than volunteers can afford.

Generative AI changed that. A viewer is an unusually good fit for AI-driven iterative development ("vibe coding"): there is a spec to read and a correct output to aim for, so the work comes down to interpreting the specification and refining the rendering until it matches. Limiting the scope to viewing also avoids the most serious risk an Office library can carry — corrupting a user's files.

So I'm building this library with AI coding agents, spec-first, and keeping it free to use. For some documents it already reproduces the desktop Office applications more faithfully than commercial libraries — and sometimes even the official Microsoft 365 web apps.

Office Open XML Viewer

Live demo

A browser-based viewer for Office Open XML documents that renders to an HTML Canvas element. The parsers are written in Rust and compiled to WebAssembly; the renderers use the Canvas 2D API. Each format also exposes a headless engine (DocxDocument / XlsxWorkbook / PptxPresentation) that renders into any caller-supplied canvas, so you can compose your own UI — scroll views, thumbnail grids, master-detail panes — instead of being locked into the built-in viewer. See the Examples section in the Storybook demo.

DOCX	XLSX	PPTX

npm install @silurus/ooxml
# or
pnpm add @silurus/ooxml

Bundler note: the Rust parsers ship as real .wasm asset files next to the JavaScript, referenced with the standard new URL('…', import.meta.url) form and fetched (streaming-compiled) at load time. Verified to work with zero config: webpack 5, Next.js (Turbopack, dev and build), Vite 8 (dev and build), Vite 7 production builds, and a plain <script type="module"> with no bundler at all. Two setups need a hand:

• Vite 7 dev server: the dependency optimizer rewrites the asset reference into its own cache path and the load fails (fixed in Vite 8). Add optimizeDeps: { exclude: ['@silurus/ooxml'] } to your vite.config — production builds are unaffected.
• esbuild / Angular CLI (whose application builder is esbuild-based): new URL asset references are not processed (esbuild#795). Copy the .wasm into your served output and point the viewer at it with the wasmUrl load option — see the Angular example for the two-step setup.

wasmUrl also serves the parser WASM from a CDN or any path you control:

new DocxViewer(canvas, { wasmUrl: 'https://cdn.example.com/docx_parser_bg.wasm' });

Bundle size note: the package is ESM-only (.mjs). npm's Unpacked Size sums every entry bundle and the standalone MathJax + STIX Two Math asset (mathjax-stix2.js, ~3 MB) that ships in the tarball, so the reported figure is much larger than any single app build. What actually lands in your app is smaller on two counts: import only the format you need (e.g. @silurus/ooxml/pptx), and the math engine is a separate entry (@silurus/ooxml/math). Its main-thread chunk is a ~1 KB loader that references the ~3 MB engine asset as a sibling file (not an inline data URL): the engine is fetched lazily, only when a document actually contains equations — and only if you imported @silurus/ooxml/math and passed it to a viewer in the first place (see Rendering equations). Never import the math entry and the loader chunk never enters your graph at all.

---

Quick Start

import { DocxViewer } from '@silurus/ooxml/docx';
import { XlsxViewer } from '@silurus/ooxml/xlsx';
import { PptxViewer } from '@silurus/ooxml/pptx';

// DOCX — caller provides the <canvas>
const canvas = document.getElementById('docx-canvas') as HTMLCanvasElement;
const docx = new DocxViewer(canvas);
await docx.load('/document.docx');
docx.nextPage();

// XLSX — viewer manages its own <canvas> + tab bar
const container = document.getElementById('xlsx-container') as HTMLElement;
const xlsx = new XlsxViewer(container);
await xlsx.load('/workbook.xlsx');

// PPTX — caller provides the <canvas>
const canvas = document.getElementById('pptx-canvas') as HTMLCanvasElement;
const pptx = new PptxViewer(canvas);
await pptx.load('/deck.pptx');
pptx.nextSlide();

Rendering equations

OMML equations (m:oMath / m:oMathPara) in .docx, .pptx and .xlsx are rendered with MathJax + STIX Two Math. That engine is ~3 MB, so it is opt-in: import the math engine from the separate @silurus/ooxml/math entry and pass it to the viewer. Pass it and equations render; omit it and the engine is referenced nowhere, so a bundler leaves it out of your build entirely (equations are simply skipped). When you do pass it, the ~3 MB engine ships as a standalone asset file next to the bundle rather than an inline data URL, and is fetched on demand — only the first time a document actually contains an equation, so equation-free documents never pay for it. It is fully self-contained: served from your own origin, no cross-origin requests.

import { DocxViewer } from '@silurus/ooxml/docx';
import { math } from '@silurus/ooxml/math';

const canvas = document.getElementById('docx-canvas') as HTMLCanvasElement;
const docx = new DocxViewer(canvas, { math }); // ← equations now render
await docx.load('/paper-with-equations.docx');

The same math engine works for every viewer (DocxViewer, PptxViewer, XlsxViewer) and every headless engine (DocxDocument, PptxPresentation, XlsxWorkbook). You inject it once where you create the object — the viewer constructor or the .load() options — and every render reuses it; it is never a per-render argument. (Excel stores "Insert > Equation" as OMML inside the shared DrawingML <xdr:txBody> grammar, so XlsxViewer renders equations embedded in shapes / text boxes the same way.)

Off-main-thread rendering

By default the headless engines parse in a worker but render on the main thread. Pass mode: 'worker' to .load() to parse and render entirely inside a Web Worker — the main thread only paints the returned ImageBitmap via a bitmaprenderer context, keeping it free for scrolling and input. It requires Worker + OffscreenCanvas.

import { PptxPresentation } from '@silurus/ooxml/pptx';

// Render entirely inside a Web Worker — the main thread only paints bitmaps.
const pres = await PptxPresentation.load('/deck.pptx', { mode: 'worker' });
const canvas = document.getElementById('pptx-canvas') as HTMLCanvasElement;
const bitmap = await pres.renderSlideToBitmap(0, { width: 960, dpr: window.devicePixelRatio });
const ctx = canvas.getContext('bitmaprenderer') as ImageBitmapRenderingContext;
ctx.transferFromImageBitmap(bitmap); // consumes the bitmap

The *ToBitmap method exists on all three engines — PptxPresentation.renderSlideToBitmap(slideIndex, opts), DocxDocument.renderPageToBitmap(pageIndex, opts), and XlsxWorkbook.renderViewportToBitmap(sheetIndex, viewport, opts) (the xlsx variant requires opts.width and opts.height, since a worker has no DOM element to measure). They work in both modes — in main mode they render to an internal OffscreenCanvas — so you can write mode-agnostic code.

Notes:

• The returned ImageBitmap is owned by the caller: transferFromImageBitmap consumes it, or call bitmap.close() when done.
• The canvas-target methods (renderSlide(canvas), renderPage(canvas), renderViewport(canvas)) are unavailable in worker mode — use the *ToBitmap variants instead.
• OMML equations require mode: 'main'; in worker mode they are skipped (with a console warning).
• Trade-off: worker mode keeps the main thread responsive, but each frame is transferred back as an ImageBitmap, so a single render can be marginally slower than mode: 'main'. Choose it for non-blocking UI, not raw speed.

Continuous scroll viewers

DocxScrollViewer and PptxScrollViewer render the whole document as one vertically-scrolling, PDF-reader-style surface instead of a single page/slide at a time. Unlike DocxViewer / PptxViewer (which take a <canvas>), the scroll viewers take a container <div> — they own the scroll host, virtualize the page/slide list (only the visible window plus a small overscan is mounted), and recycle canvases as you scroll.

import { DocxScrollViewer } from '@silurus/ooxml/docx';

const container = document.getElementById('docx-scroll') as HTMLElement;
const viewer = new DocxScrollViewer(container);
await viewer.load('/document.docx');
// viewer.scrollToPage(3);
// viewer.pageCount, viewer.topVisiblePage

import { PptxScrollViewer } from '@silurus/ooxml/pptx';

const container = document.getElementById('pptx-scroll') as HTMLElement;
const viewer = new PptxScrollViewer(container);
await viewer.load('/deck.pptx');
// viewer.scrollToSlide(2);
// viewer.slideCount, viewer.topVisibleSlide

The container must have a bounded height (e.g. height: 100vh or a flex child) so the viewer can size its scroll host to it. Base zoom fits the first page/slide width to the container width and re-fits on resize; a 0-width container defers layout until it has width. Call destroy() to tear down (a self-loaded engine is destroyed with it; an injected one is not — see below).

Desk appearance. The viewer paints each page/slide on its own white canvas with a soft drop shadow, over a transparent "desk". Style the desk and the sheet gaps without any wrapper CSS:

const viewer = new DocxScrollViewer(container, {
  background: '#f3f4f6',            // the desk behind / between pages
  gap: 24,                          // vertical gap between pages
  paddingTop: 32,                   // desk padding above the first page
  pageShadow: '0 0 0 1px #c8ccd0',  // crisp 1px "border" look (box-shadow never shifts layout)
  // pageShadow: false,             // flat pages, no shadow
});

paddingBottom, paddingLeft and paddingRight each default to gap, so the sheet sits inside a uniform desk margin; pass 0 for a flush edge.

Zoom. Ctrl/⌘ + mouse-wheel (and trackpad pinch) zooms the surface; bare-wheel still scrolls natively. Zoom is flicker-free — a rapid gesture shows a CSS preview and settles into a crisp re-render when it pauses. Bounds are the absolute scale factors zoomMin / zoomMax (default 0.1 / 4), and setScale(scale) sets it programmatically. Pass enableZoom: false to disable.

Text selection (main mode only). Pass enableTextSelection: true to overlay a transparent, selectable text layer per page/slide for native copy. In mode: 'worker' the overlay stays empty (the per-run geometry cannot cross the worker boundary) and the viewer logs one warning — use the default mode: 'main' for selectable text.

Hyperlinks. For DOCX/PPTX the link hit regions live on the text-selection overlay, so hyperlink interaction requires enableTextSelection: true; when that overlay is enabled, links are interactive by default. XLSX hit-tests cells directly, so links are interactive out of the box. An external link opens in a new tab (scheme-sanitized to http / https / mailto / tel, noopener), and an internal target navigates within the document (docx bookmark, pptx slide jump, xlsx sheet). Pass onHyperlinkClick(target) to take over the click yourself. Pass enableHyperlinks: false to disable hyperlink interactivity entirely — no hit-testing, no pointer cursor over links, no default navigation, and onHyperlinkClick is never called; links still render as authored but are inert. This applies to every viewer that supports hyperlinks (DocxViewer, DocxScrollViewer, PptxViewer, PptxScrollViewer, XlsxViewer).

Master–detail / shared engine. Inject an already-loaded headless engine so a paged viewer and a scroll viewer (or several panes) share one parse. When you inject, load() is unsupported (the engine is already loaded), the engine's own mode wins, and destroy() leaves the injected engine intact — the caller owns its lifecycle:

import { DocxDocument, DocxScrollViewer } from '@silurus/ooxml/docx';

const doc = await DocxDocument.load('/document.docx'); // parse once
const scroll = new DocxScrollViewer(container, { document: doc });
// ...also drive a thumbnail grid, a paged view, etc. from the same `doc`.
scroll.destroy(); // the injected `doc` is NOT destroyed — you own it
doc.destroy();    // release it yourself when every pane is gone

PptxScrollViewer takes the same shape with { presentation: pres } (await PptxPresentation.load(...)).

Both viewers also expose relayout() (force a re-fit when the container resizes in a way a ResizeObserver cannot see — e.g. a late web-font load), onVisiblePageChange / onVisibleSlideChange (fires when the top-most visible page/slide changes), and onError (async per-page render failures are routed here instead of crashing the scroll loop). The parse/render knobs from the headless engines (mode, useGoogleFonts, maxZipEntryBytes, math, dpr) are accepted too.

Markdown export

Every headless engine can project its document to GitHub-flavoured markdown for LLM ingestion, full-text search, or diffing — headings, lists, tables, and (for docx) footnotes / comments are preserved; layout, fonts, and positioning are dropped. The projection is compiled into the parser WASM you already ship, so it adds zero bundle weight. toMarkdown() works in both mode: 'main' and mode: 'worker' (it runs off the archive opened at load()):

import { DocxDocument } from '@silurus/ooxml/docx';

const doc = await DocxDocument.load('/document.docx');
const md = await doc.toMarkdown();

PptxPresentation.toMarkdown() (title slides → # headings, body → nested bullets, notes / comments collated) and XlsxWorkbook.toMarkdown() (each sheet → a ## SheetName pipe table) are the twins.

For a one-off conversion outside a viewer, the standalone @silurus/ooxml-markdown package exposes the low-level functions and a CLI:

import { docxToMarkdown, initDocxFromBytes } from '@silurus/ooxml-markdown';

initDocxFromBytes(wasmBytes);          // the docx parser's `_bg.wasm`
const md = docxToMarkdown(fileBytes);  // ArrayBuffer | Uint8Array | Buffer

npx ooxml-md document.docx            # → stdout
npx ooxml-md deck.pptx -o deck.md     # → file

---

Architecture diagram

flowchart TB
    subgraph build["🦀  Build-time  (Rust → WebAssembly)"]
        direction LR
        docx_rs["packages/docx/parser/src/lib.rs"]
        xlsx_rs["packages/xlsx/parser/src/lib.rs"]
        pptx_rs["packages/pptx/parser/src/lib.rs"]
        docx_rs -- wasm-pack --> docx_wasm["docx_parser.wasm"]
        xlsx_rs -- wasm-pack --> xlsx_wasm["xlsx_parser.wasm"]
        pptx_rs -- wasm-pack --> pptx_wasm["pptx_parser.wasm"]
    end

    subgraph browser["🌐  Runtime  (Browser)"]
        subgraph core_pkg["@silurus/ooxml-core  (shared primitives)"]
            CORE["renderChart · resolveFill · applyStroke\nbuildCustomPath · autoResize · shared types"]
        end
        subgraph docx_pkg["@silurus/ooxml · docx"]
            DV["DocxViewer"] --> DD["DocxDocument"]
            DD --> DW["worker.ts\n〈Web Worker — parse only〉"]
            DD --> DR["renderer.ts\n〈Canvas 2D — main thread〉"]
        end
        subgraph xlsx_pkg["@silurus/ooxml · xlsx"]
            XV["XlsxViewer"] --> XB["XlsxWorkbook"]
            XB --> XW["worker.ts\n〈Web Worker — parse only〉"]
            XB --> XR["renderer.ts\n〈Canvas 2D — main thread〉"]
        end
        subgraph pptx_pkg["@silurus/ooxml · pptx"]
            PV["PptxViewer"] --> PP["PptxPresentation"]
            PP --> PW["worker.ts\n〈Web Worker — parse only〉"]
            PP --> PR["renderer.ts\n〈Canvas 2D — main thread〉"]
        end
        DR -. uses .-> CORE
        XR -. uses .-> CORE
        PR -. uses .-> CORE
    end

    docx_wasm --> DW
    xlsx_wasm --> XW
    pptx_wasm --> PW
    DR --> canvas["<canvas>"]
    XR --> canvas
    PR --> canvas

Loading

All three formats follow the same shape: the worker parses the .docx / .xlsx / .pptx archive via WASM and posts a JSON model back to the main thread, where the renderer draws to the canvas. Rendering stays on the main thread so the canvas shares the document's FontFaceSet — an OffscreenCanvas in a worker has its own font registry and would silently fall back to a system font, producing subtly different text measurements (and wrap positions) from the installed theme webfonts. @silurus/ooxml-core holds the cross-format primitives that the three renderers all depend on: a unified chart renderer (bar / line / area / radar / waterfall), shape helpers (resolveFill, applyStroke, buildCustomPath, hexToRgba), the autoResize viewer utility, and the shared type definitions.

Key files

File	Role
packages/docx/parser/src/lib.rs	Rust WASM parser — DOCX ZIP → Document JSON
packages/xlsx/parser/src/lib.rs	Rust WASM parser — XLSX ZIP → Workbook JSON
packages/pptx/parser/src/lib.rs	Rust WASM parser — PPTX ZIP → Presentation JSON
packages/docx/src/renderer.ts	Canvas 2D rendering engine with text layout (main thread)
packages/xlsx/src/renderer.ts	Canvas 2D rendering engine with virtual scroll (main thread)
packages/pptx/src/renderer.ts	Canvas 2D rendering engine (main thread)
packages/*/src/worker.ts	Web Worker: WASM init and parsing only (one per format)
packages/*/src/viewer.ts	Public Viewer API — canvas lifecycle, navigation
packages/core/src/index.ts	Cross-format primitives — chart renderer, shape helpers, autoResize, shared types

---

Framework Examples

React 19

// React 19.1 — Vite copies the parser .wasm asset automatically; no extra plugin needed.
import { useEffect, useRef, useState } from 'react';
import { PptxViewer } from '@silurus/ooxml/pptx';

export function PptxViewerComponent({ src }: { src: string }) {
  const canvasRef  = useRef<HTMLCanvasElement>(null);
  const viewerRef  = useRef<PptxViewer | null>(null);
  const [slide, setSlide] = useState({ current: 0, total: 0 });

  useEffect(() => {
    const canvas = canvasRef.current;
    if (!canvas) return;

    const viewer = new PptxViewer(canvas, {
      onSlideChange: (i, total) => setSlide({ current: i, total }),
    });
    viewerRef.current = viewer;
    viewer.load(src);
  }, [src]);

  return (
    <div>
      <canvas ref={canvasRef} style={{ width: 800 }} />
      <button onClick={() => viewerRef.current?.prevSlide()}>‹ Prev</button>
      <span> {slide.current + 1} / {slide.total} </span>
      <button onClick={() => viewerRef.current?.nextSlide()}>Next ›</button>
    </div>
  );
}

Vue 3.5

<!-- Vue 3.5 — useTemplateRef is a 3.5+ feature -->
<script setup lang="ts">
import { useTemplateRef, onMounted, ref } from 'vue';
import { PptxViewer } from '@silurus/ooxml/pptx';

const props = defineProps<{ src: string }>();

const canvas  = useTemplateRef<HTMLCanvasElement>('canvas');
let viewer: PptxViewer | null = null;
const current = ref(0);
const total   = ref(0);

onMounted(async () => {
  viewer = new PptxViewer(canvas.value as HTMLCanvasElement, {
    onSlideChange: (i, t) => { current.value = i; total.value = t; },
  });
  await viewer.load(props.src);
});
</script>

<template>
  <div>
    <canvas ref="canvas" style="width: 800px" />
    <button @click="viewer?.prevSlide()">‹ Prev</button>
    <span> {{ current + 1 }} / {{ total }} </span>
    <button @click="viewer?.nextSlide()">Next ›</button>
  </div>
</template>

Angular 19

The Angular CLI's esbuild-based builder does not process the new URL('…', import.meta.url) asset reference the parsers use (angular-cli#22388), so the .wasm never reaches the build output — and under ng serve the dependency optimizer additionally rewrites the reference into its own cache path. Both steps below are required (the asset copy alone fixes only production builds; ng serve still 404s without wasmUrl):

// angular.json — copy the parser WASM into the served root
// (restart `ng serve` after editing this file)
"architect": {
  "build": {
    "options": {
      "assets": [
        { "glob": "*_parser_bg.wasm", "input": "node_modules/@silurus/ooxml/dist", "output": "/" },
        { "glob": "**/*", "input": "public" }
      ]
    }
  }
}

// Angular 19 — standalone component with signal-based state
import {
  Component, ElementRef, viewChild,
  signal, AfterViewInit,
} from '@angular/core';
import { PptxViewer } from '@silurus/ooxml/pptx';

@Component({
  selector: 'app-pptx-viewer',
  standalone: true,
  template: `
    <div>
      <canvas #canvas style="width: 800px"></canvas>
      <button (click)="prev()">‹ Prev</button>
      <span> {{ current() + 1 }} / {{ total() }} </span>
      <button (click)="next()">Next ›</button>
    </div>
  `,
})
export class PptxViewerComponent implements AfterViewInit {
  canvasEl = viewChild.required<ElementRef<HTMLCanvasElement>>('canvas');
  current = signal(0);
  total   = signal(0);
  private viewer?: PptxViewer;

  ngAfterViewInit(): void {
    this.viewer = new PptxViewer(this.canvasEl().nativeElement, {
      wasmUrl: '/pptx_parser_bg.wasm',
      onSlideChange: (i, t) => { this.current.set(i); this.total.set(t); },
    });
    this.viewer.load('/deck.pptx');
  }

  prev(): void { this.viewer?.prevSlide(); }
  next(): void { this.viewer?.nextSlide(); }
}

The *_parser_bg.wasm glob copies all three parsers; narrow it to pptx_parser_bg.wasm if you only use one format. If you deploy under a non-root base href, adjust wasmUrl so it resolves under your base (a relative wasmUrl is resolved against the document URL).

Svelte 5

<!-- Svelte 5 — runes syntax ($props, $state) -->
<script lang="ts">
  import { onMount } from 'svelte';
  import { PptxViewer } from '@silurus/ooxml/pptx';

  let { src }: { src: string } = $props();

  let canvas: HTMLCanvasElement;
  let viewer: PptxViewer;
  let current = $state(0);
  let total   = $state(0);

  onMount(async () => {
    viewer = new PptxViewer(canvas, {
      onSlideChange: (i, t) => { current = i; total = t; },
    });
    await viewer.load(src);
  });
</script>

<div>
  <canvas bind:this={canvas} style="width: 800px"></canvas>
  <button onclick={() => viewer?.prevSlide()}>‹ Prev</button>
  <span> {current + 1} / {total} </span>
  <button onclick={() => viewer?.nextSlide()}>Next ›</button>
</div>

SolidJS 1.9

// SolidJS 1.9
import { createSignal, onMount, onCleanup } from 'solid-js';
import { PptxViewer } from '@silurus/ooxml/pptx';

export function PptxViewerComponent(props: { src: string }) {
  let canvasEl!: HTMLCanvasElement;
  let viewer: PptxViewer | undefined;
  const [current, setCurrent] = createSignal(0);
  const [total,   setTotal  ] = createSignal(0);

  onMount(async () => {
    viewer = new PptxViewer(canvasEl, {
      onSlideChange: (i, t) => { setCurrent(i); setTotal(t); },
    });
    await viewer.load(props.src);
  });

  onCleanup(() => { /* viewer?.destroy?.() */ });

  return (
    <div>
      <canvas ref={canvasEl} style={{ width: '800px' }} />
      <button onClick={() => viewer?.prevSlide()}>‹ Prev</button>
      <span> {current() + 1} / {total()} </span>
      <button onClick={() => viewer?.nextSlide()}>Next ›</button>
    </div>
  );
}

Qwik 2

// Qwik 2.0 — dynamic import to keep WASM out of SSR bundle
import { component$, useSignal, useVisibleTask$ } from '@builder.io/qwik';
import type { PptxViewer as PptxViewerType } from '@silurus/ooxml/pptx';

export const PptxViewerComponent = component$<{ src: string }>(({ src }) => {
  const canvasRef = useSignal<HTMLCanvasElement>();
  const current = useSignal(0);
  const total   = useSignal(0);
  let viewer: PptxViewerType | undefined;

  // useVisibleTask$ runs only in the browser, never during SSR
  useVisibleTask$(async () => {
    if (!canvasRef.value) return;
    const { PptxViewer } = await import('@silurus/ooxml/pptx');
    viewer = new PptxViewer(canvasRef.value, {
      onSlideChange: (i, t) => { current.value = i; total.value = t; },
    });
    await viewer.load(src);
  });

  return (
    <div>
      <canvas ref={canvasRef} style={{ width: '800px' }} />
      <button onClick$={() => viewer?.prevSlide()}>‹ Prev</button>
      <span> {current.value + 1} / {total.value} </span>
      <button onClick$={() => viewer?.nextSlide()}>Next ›</button>
    </div>
  );
});

---

Feature Support

Word (.docx)

Category	Feature	Status
Document	Page rendering	✅
	Page size and margins	✅
	Headers / footers (default / first / even)	✅
	Section breaks (continuous / nextPage / oddPage / evenPage)	✅
	Page borders (w:pgBorders, §17.6.10 — standard line styles, offsetFrom / display / zOrder; art borders not yet supported)	✅
	Line numbering (w:lnNumType, §17.6.8)	✅
	Section vertical alignment (w:vAlign, §17.6.22)	✅
Text	Paragraphs	✅
	Bold, italic, underline, strikethrough	✅
	Font family, size, color	✅
	Hyperlinks	✅
	Superscript / subscript (w:vertAlign)	✅
	Ruby annotations / furigana (w:ruby)	✅
Formatting	Paragraph alignment (left / center / right / justify / distribute — CJK both/distribute spread by inter-character pitch, §17.18.44)	✅
	Line spacing (auto / atLeast / exact)	✅
	Document grid (w:docGrid, §17.6.5 — line pitch + East Asian character grid / 字詰め)	✅
	Margin collapsing between paragraphs	✅
	Indents and tab stops	✅
	Multi-column section layout (w:cols, §17.6.4 — newspaper-flow columns; full-width floats span all columns)	✅
	Lists (bullet and numbered, multi-level %N markers §17.9.11)	✅
	Paragraph styles (Heading 1–9, Normal, custom)	✅
	Table style w:pPr cascade (§17.7.6)	✅
	Table style borders / shading / banding (tblStylePr, cnfStyle, §17.4.7)	✅
	Table of contents (TOC field) — dot leaders, right-aligned page numbers	✅
	keepNext / keepLines / widowControl	✅
	Right-to-left text — UAX#9 bidi, w:bidi / w:rtl, complex-script formatting (w:szCs / w:bCs / rFonts@cs, §17.3.2.26), RTL lists and indents	✅
	Japanese kinsoku line breaking (w:kinsoku, §17.15.1.58 — 行頭/行末禁則)	✅
	Vertical writing (縦書き — UAX#50 vertical glyph forms, 縦中横 tate-chu-yoko runs, 、。 upper-right positioning; §17.3.2 vertical text)	✅
Elements	Tables (with borders, fills, merges, banding, alignment)	✅
	Table auto-layout by preferred widths (w:tblLayout autofit, §17.4.52; min content width)	✅
	Table indent (w:tblInd, §17.4.50)	✅
	Right-to-left table column order (w:bidiVisual, §17.4.1)	✅
	Charts (embedded DrawingML c:chart — bar / line / area / pie / doughnut / radar / scatter, via the shared core chart renderer; data labels honour dLblPos, §21.2.2.48)	✅
	Math equations (OMML m:oMath / m:oMathPara, rendered via MathJax — opt-in @silurus/ooxml/math)	✅
	Images (inline and anchored, with text wrap)	✅
	SVG images (asvg:svgBlip MS-2016 extension — vector drawn from the embedded .svg, raster fallback)	✅
	Text boxes / drawing shapes (wps:txbx, a:prstGeom — 186 preset geometries via the shared engine; connector arrow heads headEnd / tailEnd (§20.1.8.3) and prstDash dash patterns (§20.1.8.48)). Text-box paragraphs run through the same line-layout engine as body text, so kinsoku 行頭/行末禁則 (§17.15.1.58–60), UAX#9 bidi (w:bidi, §17.3.1.6), justification (§17.18.44) and tab stops (§17.3.1.37) all apply inside a box	✅
	WMF and EMF metafile images (legacy vector, incl. inside text boxes) — rasterized via a built-in player: window→viewport mapping (MS-EMF map modes, world transform), pens/brushes, poly/rect/ellipse, text-out, path clipping, and embedded DIB blits	✅
	OLE embedded objects (w:object — the baked VML v:imagedata preview is drawn; the embedded app is not run)	✅
Advanced	Footnotes — reference markers + bottom-of-page bodies with separator rule, numbered (w:footnoteReference / w:footnoteRef, §17.11)	✅
	Endnotes — reference markers + bodies at document end (w:endnoteReference, §17.11)	✅
	Page-number formats (w:pgNumType restart / format §17.6.12; PAGE \* switches — decimal / roman / letter / hex / ordinal-dash / hebrew2 / koreanLegal, §17.18.59)	✅
	Field date/time pictures (TIME / DATE field \@ format, §17.16.5.72 / .16)	✅
	w:snapToGrid opt-out of the document grid (§17.3.1.32)	✅
	Track changes (w:ins / w:del — author-coloured underline / strikethrough)	✅
	Comments — author / date / text via the document model (doc.comments, §17.13.4; not drawn on the page)	✅
	Markdown export (DocxDocument.toMarkdown() — headings, lists, tables, footnotes / comments; also @silurus/ooxml-markdown + the ooxml-md CLI)	✅
	Mail merge fields	❌ Not planned
Interaction	Text selection (transparent overlay, native copy)	✅
	In-document find (findText / findNext / findPrev / clearFind — full-text search, all hits highlighted, each match tagged with its page)	✅
	Runtime zoom (getScale / setScale / fitWidth / fitPage)	✅
	Clickable hyperlinks (overlay hit-test, onHyperlinkClick; internal bookmark / anchor navigation)	✅
	Continuous scroll viewer (DocxScrollViewer — virtualized page list, desk background / shadow, Ctrl/⌘+wheel zoom, engine injection)	✅
Loading	Password-protected files ([MS-OFFCRYPTO] Agile Encryption — load(bytes, { password }), decrypted client-side via WebCrypto; legacy Standard / Extensible encryption → typed unsupported-encryption)	✅

---

Excel (.xlsx)

Category	Feature	Status
Workbook	Multiple sheets, sheet names	✅
	Sheet tab colors (<sheetPr><tabColor> — theme / tint / indexed / rgb)	✅
Cells	Text, number, boolean, error values	✅
	Formula results (from cached <v>)	✅
	Dates (ECMA-376 date format codes)	✅
	Rich text (per-run formatting)	✅
	East-Asian furigana (<rPh> §18.4.6 + <phoneticPr> §18.4.3 — drawn when a cell opts in via ph="1"; row-level <row ph> inheritance)	✅
Formatting	Bold, italic, underline (single / double / singleAccounting / doubleAccounting), strikethrough	✅
	Superscript / subscript (vertAlign)	✅
	Font family, size, color	✅
	Cell background color (solid + gradient)	✅
	Pattern fills (gray125 / gray0625 / lightGray / mediumGray / darkGray and the 12 light* / dark* directional hatches)	✅
	Borders (thin, medium, thick, hair, double, dashed, dotted, dashDotDot, …)	✅
	Diagonal borders (diagonalUp / diagonalDown, single + double)	✅
	Horizontal / vertical alignment	✅
	Text wrapping	✅
	Japanese kinsoku line breaking in wrapped cells (行頭/行末禁則, shared core engine)	✅
	Number formats (0.00, %, #,##0, custom date/time)	✅
Structure	Merged cells	✅
	Right-to-left sheets (sheetView rightToLeft, §18.3.1.87 — mirrored grid, headers, selection, scroll)	✅
	Frozen panes	✅
	Row / column sizing (custom widths and heights)	✅
	Hidden rows / columns	✅
	Row / column outline grouping (outlineLevel / collapsed §18.3.1.73 / .13, <outlinePr> — gutter brackets, +/− collapse, numbered level buttons; view-only)	✅
Elements	Images (<xdr:twoCellAnchor>)	✅
	OLE embedded objects (<oleObjects> — the legacy VML v:imagedata preview keyed by oleObject@shapeId is drawn; an image-typed objectPr target is preferred when present, and the embedded app is not run)	✅
	SVG images (asvg:svgBlip MS-2016 extension — vector drawn from the embedded .svg, raster fallback)	✅
	Drawing shapes / text boxes (xdr:sp, xdr:txBody — 186 preset geometries via the shared engine, with avLst adjust handles)	✅
	Math equations in shapes (OMML m:oMath / m:oMathPara in xdr:txBody, incl. a14:m / mc:AlternateContent; rendered via MathJax — opt-in @silurus/ooxml/math)	✅
	Charts (bar, line, area, pie, doughnut, radar, scatter / bubble)	✅
	Chart markers (circle / square / diamond / triangle / x / plus / star / dot / dash, per-point <c:dPt> overrides; markers-only scatter series draw a marker legend key)	✅
	Chart data labels (<c:dLbl> per-point with CELLRANGE / VALUE / SERIESNAME / CATEGORYNAME field references, position l/r/t/b/ctr/outEnd)	✅
	Chart error bars (<c:errBars> X/Y direction, cust / fixedVal / stdErr / stdDev / percentage, dashed/styled lines)	✅
	Chart manual layout (<c:title><c:layout> and <c:plotArea><c:layout>)	✅
	Sparklines (x14:sparklineGroup — line / column / win-loss, with markers and high/low/first/last/negative highlights)	✅
Advanced	Conditional formatting (cellIs, colorScale, dataBar, iconSet, top10, aboveAverage)	✅
	Slicers (static, Office 2010 extension)	✅
	Pivot tables	❌ Not planned
	Cell comments / notes (classic xl/commentsN.xml + Office-365 threaded comments — red triangle indicator + author / text via the worksheet model, shown in an Excel-style hover popup)	✅
	Data validation (rules via the worksheet model; list-type dropdown arrow on the selected cell whose click opens a panel showing the allowed values — read-only)	✅
	Markdown export (XlsxWorkbook.toMarkdown() — each sheet as a ## SheetName pipe table; also @silurus/ooxml-markdown + the ooxml-md CLI)	✅
Interaction	Cell selection (single / range / row / column / all)	✅
	Excel-style row / column header highlight on selection	✅
	Shift+click to extend, Ctrl+C to copy as TSV	✅
	Text selection inside cells (transparent overlay)	✅
	onSelectionChange callback, getCellAt(x, y) API	✅
	Zoom slider (Excel-style, right of the tab bar, 10–400% with 100% centered; showZoomSlider option)	✅
	Ctrl/⌘ + mouse-wheel and trackpad-pinch zoom (in addition to the slider)	✅
	Runtime fit / zoom API (fitWidth / fitPage / getScale / setScale, in addition to the slider)	✅
	In-document find (findText / findNext / findPrev / clearFind — matches tagged with sheet + cell)	✅
	Clickable hyperlinks (onHyperlinkClick; internal defined-name / cell navigation)	✅
	Drag-to-resize columns / rows by dragging header borders (resizable option, default on) — view-only: changes the on-screen view only and never modifies the loaded file	✅
	Customizable cell-selection color (selectionColor option, setSelectionColor())	✅
Loading	Password-protected files ([MS-OFFCRYPTO] Agile Encryption — load(bytes, { password }), decrypted client-side via WebCrypto; legacy Standard / Extensible encryption → typed unsupported-encryption)	✅

---

PowerPoint (.pptx)

Category	Feature	Status
Slides	Slide rendering	✅
	Slide layout / master inheritance	✅
	Slide size (custom dimensions)	✅
	Slide background (solid, gradient, image)	✅
	Slide numbers	✅
	Speaker notes (plain text via getNotes())	✅
	Markdown export (PptxPresentation.toMarkdown() — title slides → headings, body → nested bullets, notes / comments collated; also @silurus/ooxml-markdown + the ooxml-md CLI)	✅
	Animations / transitions	❌ Not planned
Element types	Shapes (sp)	✅
	Pictures (pic)	✅
	SVG images (asvg:svgBlip MS-2016 extension — vector drawn from the embedded .svg, PNG fallback)	✅
	Groups (grpSp) with nested transforms	✅
	Connectors (cxnSp)	✅
	Tables (tbl in graphicFrame)	✅
	Charts (bar, line, area, radar, waterfall)	✅
	Charts (pie, doughnut)	✅
	Charts (scatter — scatterStyle marker / line / smooth variants)	✅
	Charts (bubble — bubbleSize per-point area scaling)	✅
	Charts (combo — bar + line with a secondary value axis on the right)	✅
	Charts (chartEx — funnel / histogram / treemap / sunburst / box & whisker)	✅
	Charts (stock — high / low / close candlesticks)	✅
	SmartArt (renders the PowerPoint-saved drawing layout dsp:drawing, or a staged fallback to a text list when no drawing part is present; no native diagram layout engine)	✅
	OLE embedded objects (p:oleObj — the baked preview p:pic is drawn; the embedded app is not run)	✅
	Video / audio (poster + interactive playback)	✅
	Ink / handwriting (p:contentPart, raster fallback)	✅
Shape geometry	186 preset shapes (prstGeom — incl. 3D presets cube / can / bevel / frame)	✅
	Custom geometry (custGeom) on shapes and pictures (clipping)	✅
	Rotation and flip (flipH / flipV)	✅
Fills	Solid fill (solidFill)	✅
	Linear / radial gradient (gradFill)	✅
	No fill (noFill)	✅
	Pattern fill (pattFill) — 30 preset bitmaps incl. pct5–pct90 / horz / vert / cross / diag / grid / brick / check / trellis	✅
	Image fill on shapes (blipFill in sp)	✅
Strokes	Solid line color and width	✅
	Dash / dot styles	✅
	Arrow heads (headEnd / tailEnd)	✅
	Compound / double lines (`<a:ln cmpd="dbl	thinThick
	Picture border (a:ln on p:pic) — stroked along the clip silhouette	✅
Shape effects	Drop shadow (outerShdw)	✅
	Glow (glow — radius + colour)	✅
	Inner shadow (innerShdw)	✅
	Soft edge (softEdge)	✅
	Reflection (reflection)	✅
	3D camera / perspective projection (scene3d camera + rot) on pictures and shapes — projected shape text is drawn but not selectable	✅
	3D contour edge (sp3d contourW / contourClr) — flat approximation	⚠️
	Bevel shading (sp3d bevelT / bevelB) — distance-field lip lit by lightRig, matte/plastic materials	✅
	3D extrusion (sp3d extrusionH / extrusionClr) — swept side-wall approximation (visible only under a tilted camera)	⚠️
Text — characters	Bold, italic, strikethrough (incl. dblStrike)	✅
	Underline styles (sng / dbl / dotted / dash / dashLong / dotDash / dotDotDash / wavy / wavyDbl and *Heavy variants)	✅
	Per-run underline colour (uFill / uFillTx)	✅
	Font family, size, color	✅
	East Asian font (rPr > a:ea — separate typeface for CJK glyphs)	✅
	Symbol font runs (a:sym — e.g. Wingdings / Webdings glyphs)	✅
	Caps transform (all / small)	✅
	Letter spacing (spc)	✅
	Superscript / subscript	✅
	Hyperlinks (hlinkClick — theme hlink colour + auto underline)	✅
	Text shadow (rPr > effectLst > outerShdw)	✅
	Text outline (rPr > a:ln)	✅
	WordArt text warps (a:prstTxWarp, §20.1.9.19 — all 40 presets, per-glyph envelope fit incl. Follow Path)	✅
	Text highlight / marker (a:highlight — §21.1.2.3.4)	✅
	Math equations (OMML m:oMath / m:oMathPara, incl. a14:m / mc:AlternateContent; STIX Two Math via MathJax — opt-in @silurus/ooxml/math)	✅
Text — paragraphs	Horizontal alignment (left / center / right / justify)	✅
	Vertical anchor (top / center / bottom)	✅
	Line spacing (spcPct, spcPts)	✅
	Space before / after paragraph	✅
	Bullet points (character, auto-numbered, and picture a:buBlip §21.1.2.4.2)	✅
	Tab stops	✅
	Indent / margin	✅
	Vertical text (bodyPr@vert — vert / vert270 / eaVert)	✅
	Right-to-left text — UAX#9 bidi engine, pPr@rtl, RTL bullets, bodyPr@rtlCol column order, tblPr@rtl tables	✅
Text — body	Text padding (insets)	✅
	normAutoFit (shrink to fit)	✅
	spAutoFit (expand box; suppresses wrap when text fits in one line)	✅
	Word wrap / no wrap	✅
	Japanese kinsoku line breaking (a:pPr@eaLnBrk, §21.1.2.2.7 — 行頭/行末禁則, shared core engine)	✅
	Multi-column text body (numCol / spcCol — balanced flow)	✅
	Theme object-default inheritance (<a:objectDefaults><a:txDef|spDef> bodyPr fallback)	✅
Tables	Cells, rows, columns	✅
	Cell merges (horizontal / vertical)	✅
	Cell borders	✅
	Cell fills (solid / gradient)	✅
	Cell diagonal lines (lnTlToBr / lnBlToTr)	✅
	Table theme styles (74 built-in PowerPoint presets)	✅
Theme	Scheme colors (dk1/lt1/accent1–6)	✅
	Font scheme (+mj-lt, +mn-lt)	✅
	lumMod / lumOff / alpha transforms	✅
Interaction	Text selection (transparent overlay, native copy)	✅
	In-document find (findText / findNext / findPrev / clearFind — matches tagged with slide)	✅
	Runtime zoom (getScale / setScale / fitWidth / fitPage)	✅
	Clickable hyperlinks (onHyperlinkClick; internal slide-jump navigation)	✅
	Continuous scroll viewer (PptxScrollViewer — virtualized slide list, desk background / shadow, Ctrl/⌘+wheel zoom, engine injection)	✅
Loading	Password-protected files ([MS-OFFCRYPTO] Agile Encryption — load(bytes, { password }), decrypted client-side via WebCrypto; legacy Standard / Extensible encryption → typed unsupported-encryption)	✅

---

A note on text selection. Across DOCX / PPTX / XLSX, text selection is currently implemented by rendering glyphs to the canvas while overlaying a transparent DOM layer that mirrors the canvas text positions for native browser selection. This dual-layer approach is a deliberate stop-gap: once the Canvas drawElement API (proposed in WICG/html-in-canvas, currently in Chromium Origin Trial) ships across browsers, the project plans to migrate to a single DOM-as-source-of-truth pipeline where the canvas mirrors the DOM directly — eliminating the duplication while keeping z-order correctness and native selection / a11y.

---

Companion packages

• packages/markdown/ — @silurus/ooxml-markdown and the ooxml-md CLI convert .pptx / .docx / .xlsx to GitHub-flavoured markdown via the workspace WASM parsers. Same projection used by the MCP server (~21× smaller than the raw XML on the demo deck, ~8% bigger than a flat-text extractor). Includes a node20-based GitHub Action for bulk repo-wide conversion.
• packages/node/ — Node-side parsers (@silurus/ooxml-node) exposing parsePptx / parseDocx / parseXlsx / parseXlsxAllSheets against the workspace WASM artifacts, with no DOM or Web Worker dependency. Useful for CI checks, headless rendering pipelines, and CLI tools. Includes an ooxml-thumbnail CLI (pptx-only first pass; requires skia-canvas).
• packages/vscode-extension/ — VS Code extension (ooxml-viewer) that registers CustomEditorProviders for .docx, .xlsx, and .pptx, and (opt-in) auto-installs and registers the ooxml-mcp-server so AI coding agents in the same window (Copilot Agent mode, Claude, …) can read those files via dedicated tools. The preview is offline by default; an opt-in ooxmlViewer.useGoogleFonts setting (off, and force-disabled in untrusted workspaces) surfaces the library's metric-compatible font substitution, widening the webview CSP to the Google Fonts CDN only while enabled.
• packages/mcp-server/ — Rust MCP server (ooxml-mcp-server) exposing the parsers as tools for AI agents (Claude, Copilot, Codex, etc.). Provides structured queries (docx_get_structure, xlsx_get_cell_range, pptx_get_slide_structure, …) so agents can inspect OOXML files without shelling out to unzip. Prebuilt binaries are attached to each GitHub Release for macOS / Linux / Windows; the VS Code extension downloads them on demand.

---

Development

# Install dependencies
pnpm install

# Build all WASM parsers (requires Rust + wasm-pack)
pnpm build:wasm

# Start Storybook dev server (port 6006)
pnpm storybook

# Type-check all packages
pnpm typecheck

# Run visual regression tests (local only — not run in CI)
pnpm vrt
# Adopt the current rendering as the new reference baseline
UPDATE_REFS=1 pnpm vrt

# Build the library
pnpm build

WASM build (individual packages)

cd packages/docx/parser && wasm-pack build --target web && cp pkg/docx_parser_bg.wasm  pkg/docx_parser.js  ../src/wasm/
cd packages/xlsx/parser && wasm-pack build --target web && cp pkg/xlsx_parser_bg.wasm  pkg/xlsx_parser.js  ../src/wasm/
cd packages/pptx/parser && wasm-pack build --target web && cp pkg/pptx_parser_bg.wasm pkg/pptx_parser.js ../src/wasm/

Security & Privacy

• Canvas-only rendering. Documents are decoded and drawn to an HTMLCanvasElement. No script, link, form, or other active content from the source file is executed or injected into the DOM.
• ZIP decompression cap. Each entry in the source archive is limited to 512 MiB of uncompressed output by default to block zip-bomb DoS. Override per viewer with maxZipEntryBytes (bytes) — raise it for legitimate decks with large embedded media, lower it to tighten the budget for untrusted input:

  new PptxViewer(canvas, { maxZipEntryBytes: 64 * 1024 * 1024 }); // 64 MiB

  Supported uniformly by DocxViewer, PptxViewer, and XlsxViewer. Zero / negative values fall back to the default.
• No network by default. The library does not send telemetry or analytics, and does not contact third-party services unless you ask it to. In particular, theme webfonts, Office font metric substitutes (Carlito/Caladea), and the script fallback fonts are not loaded from Google Fonts unless you pass useGoogleFonts: true to the relevant Viewer / load(...) options — supported uniformly by DocxViewer, PptxViewer, and XlsxViewer. When enabled, fonts for non-Latin scripts are supplied on demand from Noto families so text does not fall back to tofu: Arabic (Noto Naskh/Sans Arabic), CJK (Noto Sans/Serif KR · SC · TC · JP, picked per document language so shared Han glyphs take the right shapes), Cyrillic (Noto Sans/Serif), Hebrew (Noto Sans/Serif Hebrew, RTL), Thai (Noto Sans Thai) and Devanagari (Noto Sans Devanagari). No font binaries ship in the bundle. Enabling this option causes the end-user's browser to send an HTTP request (IP and User-Agent) to fonts.googleapis.com, which may have GDPR implications for your application — consider self-hosting the required fonts via @font-face instead.
• XML parsing. Uses roxmltree, which does not resolve external entities (XXE-safe by default).
• Encrypted OOXML ([MS-OFFCRYPTO] Agile Encryption). Password-protected .docx / .xlsx / .pptx files are OLE2/CFB containers, not ZIPs. Pass password to load(...) and the file is decrypted client-side via WebCrypto — no bytes and no password leave the browser:

  const doc = await DocxDocument.load(bytes, { password: 'secret' });

  Key derivation (SHA-512 spin, commonly 100,000 iterations) and AES-CBC segment decryption run on the main thread and add roughly a second before parsing. Failures are typed OoxmlErrors: no password on an encrypted file → encrypted, wrong password → invalid-password, a non-Agile scheme (legacy Standard / Extensible encryption, or an encrypted legacy binary .doc/.xls/.ppt) → unsupported-encryption. Note: decryption recovers the plaintext but does not verify the file's HMAC data-integrity tag ([MS-OFFCRYPTO] §2.3.4.14), so tampering with the ciphertext is not detected — treat decrypted output from untrusted sources with the same care as any other input.

License

MIT

Third-Party Notices

The library's own code is MIT-licensed. It also bundles a small set of permissively-licensed third-party components — see THIRD_PARTY_NOTICES.md (included in the npm tarball) for the full list and license texts. Highlights:

• MathJax + STIX Two Math (Apache License 2.0) — the equation-rendering engine behind the opt-in @silurus/ooxml/math entry described in Rendering equations. It ships in the tarball as a standalone ~3 MB asset but is never loaded by a consuming app unless that app imports @silurus/ooxml/math and the viewer is handed a document that actually contains an equation.
• Rust crate dependencies of the WASM parsers (docx/pptx/xlsx) — all MIT / Apache-2.0 (or compatible permissive licenses), no copyleft.