PDF Chisel

Cross-platform desktop PDF editor with WYSIWYG text and image editing.
Fully offline — no cloud, no subscriptions, no account required.

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Download

Pick the installer for your operating system:

Operating System	Download	Notes
Windows	Download for Windows	Run the .exe installer and follow the prompts
macOS (Apple Silicon)	Download for Mac (M1/M2/M3)	Open the .dmg, drag PDF Chisel to Applications
macOS (Intel)	Download for Mac (Intel)	Open the .dmg, drag PDF Chisel to Applications
Linux	Download for Linux	Make executable: chmod +x *.AppImage, then run

Not sure which Mac you have? Click the Apple menu () → About This Mac. If the chip says "Apple M1" / "M2" / "M3" etc., choose Apple Silicon. Otherwise choose Intel.

All downloads are also available on the Releases page.

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Features

• Edit text directly on the PDF — double-click any text to modify it
• Replace images — swap embedded images with your own PNG or JPEG files
• Undo / Redo — full edit history with Ctrl+Z / Ctrl+Shift+Z
• Multi-page — navigate, zoom, and edit any page
• Save & Save As — Ctrl+S overwrites; Ctrl+Shift+S saves a copy
• Thumbnails — sidebar page previews for quick navigation
• 100% offline — no internet connection needed, your files never leave your computer
• Open source — MIT licensed

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For Developers

Built with Electron, PDFium (native N-API addon), and TypeScript.

Quick Start

npm install
npm start

Development mode (DevTools open):

npm run dev

Build

# Compile TypeScript only
npm run build

# Build native PDFium addon (requires node-gyp and PDFium headers)
npm run build:native

# Package for current OS
npm run pack

# Create distributable installer
npm run dist

Packaging Targets

Platform	Format	Notes
Windows	MSI (WiX) + NSIS	electron-wix-msi for enterprise deployment
macOS	DMG	Hardened runtime, notarised
Linux	AppImage	Universal, no-install

Architecture

src/
├── main/            # Electron main process
│   ├── index.ts           # App lifecycle, window creation, CSP enforcement
│   ├── ipc-handlers.ts    # IPC handler registration (typed, validated)
│   └── pdfium.ts          # PdfiumEngine façade (wraps native addon)
├── preload/         # Preload bridge (contextBridge → window.api)
│   └── index.ts
├── renderer/        # UI (no Node/Electron access)
│   ├── index.html         # Document shell with toolbar, canvas viewer
│   ├── styles.css         # Dark theme, canvas, overlays
│   └── app.ts             # Viewer, zoom/pan, editing, undo/redo
└── shared/          # Types, constants, IPC schema shared across processes
    ├── constants.ts
    └── ipc-schema.ts
native/
└── pdfium/          # C++ N-API addon wrapping PDFium
    ├── binding.gyp
    └── src/

PDFium Engine

The rendering and editing engine is PDFium (Chromium's PDF library), exposed to Node.js via a native N-API addon. The PdfiumEngine TypeScript façade manages document handles, validates inputs, normalises errors, and provides typed async methods.

Key features:

• Canvas rendering: Pages rendered to RGBA bitmaps via FPDF_RenderPageBitmap
• LRU bitmap cache: Bounded by MAX_BITMAP_CACHE_BYTES (256 MB default)
• Render queue: Concurrent renders limited by RENDER_CONCURRENCY_LIMIT
• Object inspection: listPageObjects returns text/image bounding boxes
• Text editing: editTextObject modifies glyph content via PDFium edit API
• Image replacement: replaceImageObject swaps embedded images (PNG/JPEG)
• Save: FPDF_SaveAsCopy serialisation with dirty-state tracking

Security Model

Layer	Protection
nodeIntegration	Disabled — renderer has no Node access
contextIsolation	Enabled — preload runs in isolated context
sandbox	Enabled — OS-level renderer sandboxing
CSP	Enforced via response headers and meta tag
IPC	Typed schema; channel allow-list; unknown rejected
Navigation	Blocked; window.open denied
Single instance	Second launch focuses existing window
Offline	No network calls; auto-update disabled by default

Packaging & Distribution

Build Installers

# Build for current platform
npm run dist

# Build for specific platform
npm run dist:win     # Windows NSIS installer
npm run dist:mac     # macOS DMG
npm run dist:linux   # Linux AppImage

Installers are written to the release/ directory.

Windows MSI (Enterprise)

For enterprise environments requiring MSI packages:

# 1. Build unpacked app first
npm run pack

# 2. Compile MSI (requires WiX Toolset v3)
npm run build:msi

Prerequisites: Install WiX Toolset v3 and ensure the WIX environment variable is set or WiX bin/ is on PATH.

Native Addon in Packaged Builds

The native PDFium addon (pdfium.node + shared library) is automatically extracted from the asar archive via asarUnpack. The addon loader in src/main/pdfium.ts detects packaged mode (app.isPackaged) and resolves the path to app.asar.unpacked/native/pdfium/build/Release/.

Code Signing & Notarization

Windows (Authenticode)

Set the following environment variables before running npm run dist:win:

Variable	Description
CSC_LINK	Path to .pfx certificate file (or base64-encoded)
CSC_KEY_PASSWORD	Certificate password
WIN_CSC_LINK	(optional) Override for Windows-specific cert

electron-builder will sign the EXE automatically when these are set.

macOS (Apple Notarization)

Set the following environment variables:

Variable	Description
CSC_LINK	Path to .p12 Developer ID certificate (or base64)
CSC_KEY_PASSWORD	Certificate password
APPLE_ID	Apple ID email for notarization
APPLE_APP_SPECIFIC_PASSWORD	App-specific password (generate at appleid.apple.com)
APPLE_TEAM_ID	10-character Team ID from developer.apple.com

The build uses build/entitlements.mac.plist which grants:

• com.apple.security.cs.allow-jit — required by V8/Chromium
• com.apple.security.cs.allow-unsigned-executable-memory — required by Electron
• com.apple.security.cs.disable-library-validation — required for the prebuilt PDFium shared library

Linux

No code signing is typically required for AppImage distribution. For package managers (deb, rpm), GPG signing can be configured separately.

CI/CD Notes

• Store signing certificates as encrypted secrets in your CI system (GitHub Actions, Azure DevOps, etc.)
• Never commit .pfx, .p12, or password files to the repository
• The publish field in package.json is set to null (auto-update disabled). Set it to a GitHub/S3/generic provider when ready to enable auto-updates.

License

MIT