Overview: Kopia is an open-source backup and restore tool designed for users who need control over their data’s security, location, and efficiency. Unlike traditional image-based backup solutions, Kopia operates at the file level, creating encrypted snapshots of specific directories or files rather than entire system images. It supports Windows, macOS, and Linux, making it ideal for developers, sysadmins, and power users managing heterogeneous environments. With built-in deduplication and compression, Kopia minimizes storage costs while maintaining full data integrity. The tool provides both a command-line interface for automation and scripting, and a graphical user interface for ease of use—ensuring accessibility for both technical and non-technical users. Kopia emphasizes user-controlled end-to-end encryption, meaning only you hold the decryption keys—no third-party provider can access your data.
Kopia’s architecture allows backups to be stored in a wide variety of locations, including S3-compatible clouds (like AWS, MinIO), Azure Blob Storage, Backblaze B2, Google Cloud Storage, WebDAV, SFTP servers, and even local disks. It also integrates with Rclone for experimental support of Dropbox, OneDrive, and Google Drive. This flexibility makes Kopia a compelling alternative to proprietary backup services like Backblaze or CrashPlan, especially for those who want full ownership of their data without vendor lock-in.
What You Get
- End-to-end encryption - All data is encrypted client-side before leaving your machine using AES-256, with user-controlled encryption keys. No cloud provider or third party can access your unencrypted data.
- Data deduplication - Kopia identifies and stores only unique file chunks across snapshots, reducing storage usage significantly—especially useful for large directories with frequent changes.
- Compression - Files are compressed using Zstandard (zstd) before storage, further reducing bandwidth and cloud storage costs.
- Multi-storage support - Backups can be saved to Amazon S3, Azure Blob, Google Cloud Storage, Backblaze B2, WebDAV, SFTP, Rclone-compatible services (Dropbox, OneDrive), or local directories.
- CLI and GUI interfaces - Full-featured command-line tools for automation and scripting, plus a modern desktop GUI for visual snapshot management and restores.
- Error correction - Built-in Reed-Solomon erasure coding to detect and repair corrupted data blocks in storage, improving reliability on unreliable or remote storage systems.
- Multi-machine backup to single repository - Multiple machines can back up to the same storage location using separate repositories, enabling centralized management without data mixing.
Common Use Cases
- Building a secure personal backup system for home users - A user backs up their Documents, Photos, and Projects folders to Google Cloud Storage using Kopia’s CLI, enabling encrypted, deduplicated backups with automatic scheduling via cron.
- Creating a multi-tenant SaaS dashboard with encrypted logs - A developer uses Kopia to back up application logs and configuration files from multiple servers to a private S3 bucket, ensuring compliance with data residency regulations while minimizing storage costs via deduplication.
- Problem: High cloud backup costs due to redundant files → Solution: Kopia’s deduplication - A team backing up 50GB of daily code snapshots was spending $200/month on cloud storage; after switching to Kopia, costs dropped to $15/month due to 90% deduplication across versions.
- DevOps teams managing microservices across multiple cloud providers - A DevOps team configures Kopia to back up Kubernetes manifests and Helm charts from AWS, Azure, and GCP clusters into a single Backblaze B2 bucket using S3-compatible APIs, with automated nightly snapshots and encrypted key management via HashiCorp Vault.
Under The Hood
Kopia is a modern, secure backup solution that combines a powerful command-line interface with a rich web-based UI, offering seamless cross-platform compatibility and robust encryption. It is designed to provide flexible and efficient data backup capabilities across diverse environments.
Architecture
Kopia follows a modular, layered architecture that supports both CLI and graphical user interfaces with clear separation of concerns.
- The system uses a command-driven pattern where each CLI subcommand is encapsulated in its own file, promoting modularity and scalability.
- Core functionality is separated from presentation layers through well-defined modules for repository management and UI components.
- Dependency injection and configuration-driven approaches support extensibility and maintainability across different deployment environments.
Tech Stack
The project leverages Go for core functionality and JavaScript with Electron for the user interface.
- Built predominantly in Go, with a JavaScript-based Electron UI and React for frontend experiences.
- Integrates Electron for desktop app development, electron-updater for auto-updates, and electron-store for persistent storage.
- Uses Electron Builder for cross-platform packaging and Makefiles for build automation.
- Employs Playwright for end-to-end testing and Prettier for code formatting and linting.
Code Quality
The project emphasizes comprehensive testing and consistent error handling across its modules.
- Extensive test coverage includes integration, compatibility, and end-to-end scenarios to ensure reliability.
- Error handling is systematically implemented with clear patterns in both Go and JavaScript components.
- Code maintains consistency in naming and architectural styles, though some legacy JavaScript and duplicated test files exist.
What Makes It Unique
Kopia distinguishes itself through its combination of secure backup capabilities and a modern UI approach.
- Combines a powerful CLI with an intuitive web-based UI, enabling flexible usage across platforms.
- Offers advanced encryption and storage abstraction that sets it apart from traditional backup tools.
- Provides cross-platform support through Electron-based UI and modular Go backend for broad compatibility.