Fix broken fonts in PowerPoint — in one click.

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EN · Font won't change in PowerPoint? We fix it.
RU · Шрифт не меняется в PowerPoint? Мы починим.
UK · Шрифт не змінюється в PowerPoint? Ми виправимо.
ZH · PowerPoint 中字体无法更改？我们来修复。
DE · Schriftart ändert sich nicht in PowerPoint? Wir reparieren es.
ES · ¿La fuente no cambia en PowerPoint? Lo arreglamos.
FR · La police ne change pas dans PowerPoint ? On répare ça.

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Backstory

I'm currently writing academic papers, and part of the process involves redrawing figures in PowerPoint so they can later be inserted into Word. Don't ask me why — that's just how the workflow goes.

At some point I ran into a maddening issue: when you import shapes or figures into .pptx, the text inside them refuses to change font. You select everything, pick Arial — nothing happens. The font dropdown shows one thing, the slide shows another. It's completely broken.

This isn't a one-off thing. When you have dozens of figures to process, doing it manually is not an option. I've always solved problems like this with code — so I dug into the .pptx XML, found the root causes (CJK language attributes, theme font references, broken inheritance chains), and built a tool to fix it automatically.

That tool is PowerPain.

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The Problem

PowerPoint silently ignores your font changes in these common scenarios:

Problem	Root Cause	What PowerPain Does
Font doesn't change via UI	lang="zh-CN" → PowerPoint reads <a:ea>, ignores <a:latin>	Sets lang="en-US", writes explicit <a:latin> and <a:ea>
Theme font overrides everything	+mj-lt / +mn-lt references in run properties	Replaces all theme references with target font
CJK font in theme	等线, 等线 Light in majorFont/minorFont	Normalizes theme1.xml directly
Layout/master inheritance	Fonts defined in layouts override slide-level settings	Processes all layers: slides, layouts, masters, themes

Features

• One-click fix — upload .pptx, get fixed file back
• 100% client-side — all processing runs in your browser via JSZip + DOMParser, files never leave your device
• Deep normalization — processes a:rPr, a:defRPr, a:endParaRPr across all XML files
• Theme repair — fixes majorFont/minorFont in theme files
• 11 font choices — Arial, Calibri, Times New Roman, Helvetica, Verdana, Tahoma, Georgia, Segoe UI, Roboto, Open Sans, Inter
• Zero upload — nothing is sent to any server, ever
• 7 languages — EN, RU, UK, ZH, DE, ES, FR
• Privacy-first — no accounts, no tracking, no analytics
• Modern UI — dark theme, PowerPoint color palette, responsive design

Tech Stack

Layer	Technology	Why
Runtime	Bun	Fastest JS runtime, native TypeScript
Static Server	Hono	14KB, fastest Bun-native HTTP framework
PPTX Processing	JSZip + DOMParser (browser)	Client-side ZIP + XML manipulation, no server needed
Frontend	Vanilla HTML/CSS/JS	No framework overhead for a single page
QR Code	qrcode	MIT-licensed, SVG generation

All dependencies are MIT-licensed.

Quick Start

# Clone
git clone https://github.com/yatskovskyi/PowerPain.git
cd PowerPain

# Install
bun install

# Run
bun run start

Open http://localhost:3000

Development (auto-reload)

bun run dev

Project Structure

PowerPain/
├── src/
│   ├── server.ts              # Hono server — static files, QR API, security headers
│   └── public/
│       ├── index.html          # Single-page UI with full SEO
│       ├── style.css           # Dark theme, PowerPoint palette
│       ├── app.js              # Client-side PPTX processing, i18n, drag&drop
│       ├── jszip.min.js        # JSZip library for in-browser ZIP handling
│       ├── 404.html            # Custom 404 page
│       ├── robots.txt          # Search engine + AI bot rules
│       ├── sitemap.xml         # XML sitemap
│       └── img/                # Favicon, OG image, donate photo
├── package.json
├── tsconfig.json
├── LICENSE                     # MIT
└── README.md

Architecture

All PPTX processing happens entirely in the browser. The server only serves static files and the donation QR code.

How client-side processing works

1. User drops a .pptx file
2. JSZip unpacks the archive in the browser
3. DOMParser parses each XML file (slides, layouts, masters, themes)
4. JavaScript normalizes fonts: fixes lang attributes, replaces theme references (+mj-lt, +mn-lt), sets explicit <a:latin> and <a:ea> typefaces
5. XMLSerializer converts the DOM back to XML strings
6. JSZip repacks everything into a new .pptx blob
7. User downloads the fixed file — nothing was ever uploaded

Server API

The server is minimal — it only has one API endpoint:

GET /api/qr

Returns the donation QR code as SVG.

Environment

Variable	Default	Description
PORT	3000	Server port

How to Verify

1. Open a PowerPoint file with CJK font issues
2. Upload it to PowerPain
3. Download the fixed file
4. Open in PowerPoint — fonts should now be changeable
5. Check: lang attributes should be en-US, no +mj-lt references remain

Security

• CSP — strict Content-Security-Policy (self + Google Fonts only)
• HSTS — enforced HTTPS with 1-year max-age
• X-Frame-Options: DENY — clickjacking protection
• No server processing — zero attack surface for file uploads
• Rate limiting — dotfile / sensitive path blocking

SEO & Discoverability

• Full meta tags (OG, Twitter Card, JSON-LD)
• FAQPage structured data for rich snippets
• WebApplication schema markup
• Hreflang tags for 7 languages
• XML sitemap
• robots.txt with AI crawler instructions

Contributing

Issues and PRs welcome at github.com/yatskovskyi/PowerPain.

License

MIT — Dmytro Yatskovskyi

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If PowerPain saved your day — consider supporting the project

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