BundlePack

BundlePack is a native macOS and Windows utility for packing files and folders into shareable .bundlepack archives with custom thumbnails. Each thumbnail travels with its package and appears in Finder and Windows Explorer, making packages easy to recognize at a glance. Packages can be created and opened on either platform, encrypted for privacy (the default), or stored as standard ZIP-compatible archives.

Highlights

• Give each package a custom thumbnail that appears in Finder and Windows Explorer.
• Preview an animated GIF icon on Create and play it on the validated Open screen while system thumbnails stay static.
• Add multiple files and folders with a file picker or drag and drop.
• Encrypt file names, metadata, ZIP structure, and file contents with AES-256-GCM.
• Create unencrypted .bundlepack files that remain compatible with standard ZIP tools.
• Generate strong passwords with configurable length, digit count, and symbol count.
• Open .bundlepack files by double-clicking, choosing a file, or dragging one into the app.
• Follow percentage progress and cancel long create, unlock, and extraction operations.
• Exchange packages between the native SwiftUI macOS app and native WinUI 3 Windows app.
• Run natively on Apple silicon, Intel Macs, x64 Windows, and ARM64 Windows.

macOS Screenshots

The screenshots below show the macOS application. The Windows application provides the same create and open workflows with native Windows controls.

Initial Views

Create a new package	Open an existing package

Create Workflow

Filled package details	Built-in password generator

The Create screen accepts files, folders, and a custom package icon by drag and drop. Encrypted packages can use a manually entered password or the built-in generator.

Open Workflow

Unlock an encrypted package	Review and extract validated contents

Platform Guides

The application code and platform-specific documentation are kept together.

Platform	Native implementation	Requirements, build, and integration guide
macOS	Swift, SwiftUI, AppKit, CryptoKit	macOS/README.md
Windows	C#, WinUI 3, .NET cryptography	Windows/README.md

Pull requests and pushes to main are checked on both operating systems by GitHub Actions. Windows opens the checked-in macOS fixtures and creates Windows fixtures; macOS then opens those Windows-generated files. Pull requests run these lightweight tests and dependency review. Pushes to main additionally run C# and Swift CodeQL; those analysis builds also compile the Windows x64 and macOS universal applications. CI does not retain application or installer artifacts.

Pushing a v<version> tag that matches the synchronized project version and points to a commit on the default branch runs the full native builds and installer checks, then creates or updates a GitHub prerelease. The release gate also opens Windows-generated fixtures on macOS. CodeQL is limited to pushes to main. Versioned applications, installers, SHA-256 checksums, and GitHub build-provenance attestations remain available with the release.

See Docs/RELEASE.md before publishing source or binaries. Automated applications are ad-hoc signed or unsigned test builds, not trusted end-user binaries.

Package Format

The complete binary and ZIP layout is documented in Docs/FORMAT.md. The format is platform-neutral, and the Swift and C# implementations independently enforce the same encryption, archive, metadata, and portability rules.

Encrypted

An encrypted package exposes only its public package icon and container parameters. The complete inner ZIP archive is encrypted, including file names, metadata, ZIP structure, and file contents.

Sample.bundlepack
├── fixed header
├── public icon.png
└── AES-256-GCM encrypted chunks
    └── inner.zip
        ├── icon.png
        ├── manifest.json
        ├── animation.gif (optional)
        └── payload/

Keys are derived with PBKDF2-HMAC-SHA256 using 600,000 iterations. The archive is authenticated in 4 MiB chunks, with a unique nonce and authentication tag for every chunk. Decryption fails if the password is wrong or the package has been modified.

The public icon is intentionally not encrypted because Finder and Explorer need it for thumbnails. Use the default icon if a custom image could reveal private information.

Animated GIFs keep a static PNG first-frame thumbnail for Finder, Quick Look, and Explorer. BundlePack plays a validated GIF in the Create preview and after the inner archive has been validated on Open; encrypted packages therefore remain static until they are unlocked. Playback respects the system's reduced-motion/animation setting. Animated WebP is currently out of scope.

Unencrypted

An unencrypted .bundlepack file is a standard ZIP archive. Rename it to .zip to open it with a regular archive utility. File names, metadata, and contents are available to ZIP-capable tools and file scanners.

Security Boundaries

BundlePack rejects absolute archive paths, .. traversal, symbolic links, encrypted ZIP entries, unsupported compression methods, duplicate output paths, and packages that exceed extraction limits. Passwords are not saved, and there is no password recovery mechanism.

Share the password through a different channel from the package. BundlePack is not a substitute for secure transport, endpoint security, or a reviewed backup strategy.

Current archive limits:

• fewer than 10,000 entries;
• no individual file of 4 GB or more;
• no more than 20 GB after expansion;
• bounded UTF-8 display metadata and package-icon inputs;
• no ZIP64 inner archives.

Project Layout

See Docs/ARCHITECTURE.md for component ownership, compatibility gates, and the format-change checklist.

macOS/      native macOS app, Xcode project, scripts, tests, and platform guide
Windows/    native Windows app, core library, shell integration, tests, and platform guide
Docs/       shared architecture, file-format, release, and screenshot documentation
Fixtures/   checked-in cross-platform compatibility packages
Scripts/    repository-wide cleanup, icon generation, and metadata verification

The platform directories intentionally mirror each other at the repository root. Cross-platform contracts, fixtures, tooling, and repository-wide documentation remain outside them.

Project Status

BundlePack is experimental. Review the format and both cryptographic implementations before relying on BundlePack for high-value or irreplaceable data.

• See SECURITY.md to report vulnerabilities privately.
• See CONTRIBUTING.md for development and pull-request guidance.
• See CHANGELOG.md for release notes.

License

BundlePack is available under the MIT License.