Jellyfin is a free and open-source media system designed to give users full control over their digital media libraries. It serves as a self-hosted alternative to proprietary platforms like Plex and Emby, offering a complete backend server with a web-based interface for streaming movies, TV shows, music, and more to any device. Born from the 3.5.2 release of Emby and rewritten in .NET, Jellyfin ensures cross-platform compatibility while remaining entirely free with no paywalls or feature restrictions. It’s ideal for users who value privacy, data ownership, and community-driven development over commercial cloud-based solutions.
What You Get
- Self-hosted media server - Run your own media streaming backend on any platform (Windows, Linux, macOS) without relying on third-party cloud services.
- Web-based client with API access - Access your media library through a responsive web interface or integrate via the fully documented RESTful API at /api-docs/swagger/index.html.
- Built-in transcoding with FFmpeg - Automatically transcode media files to match device capabilities using bundled or system-installed FFmpeg.
- Multi-user support with libraries and profiles - Create separate user accounts, assign library access, and customize playback settings per user.
- Cross-platform server compatibility - Runs on .NET 9.0 and supports installation via Docker, package managers, or direct source build.
- Open API documentation - Full Swagger UI available at
http://localhost:8096/api-docs/swagger/index.html for developers integrating with Jellyfin.
Common Use Cases
- Building a home media server - Hosting a personal collection of 500+ movies and TV shows on a NAS or old PC, accessible from smartphones, smart TVs, and game consoles without subscription fees.
- Replacing Plex or Emby in a privacy-focused household - Eliminating data collection and telemetry by running an open-source alternative that stores all metadata locally.
- Problem → Solution flow: Media files incompatible with smart TVs → Jellyfin auto-transcodes them - A user has MKV and FLAC files that won’t play on their Roku; Jellyfin detects device capabilities and transcodes them in real-time to H.264/AAC for seamless playback.
- Team collaboration on media infrastructure - DevOps teams managing media servers across multiple cloud providers or on-premises systems using Docker containers and automated CI/CD pipelines.
Under The Hood
Jellyfin is an open-source media server designed to provide a privacy-focused, extensible platform for organizing and streaming digital media across multiple devices. It emphasizes cross-platform compatibility and offers a rich set of features for managing large media libraries.
Architecture
Jellyfin follows a layered architecture that promotes modularity and maintainability by separating concerns across distinct system components.
- The system uses a layered pattern with clear divisions between presentation, business logic, and data access layers
- Modules are organized by domain focus such as audio naming, video processing, and metadata handling
- Strategy and factory design patterns are applied to manage format-specific parsers and resolvers
- Dependency injection and interface-based contracts support loose coupling between components
Tech Stack
Jellyfin is built primarily using C# within the .NET ecosystem, leveraging a wide range of libraries and frameworks to deliver its functionality.
- The core is developed in C# with extensive use of .NET runtime and associated frameworks for cross-platform support
- Key dependencies include ServiceStack and other .NET libraries for backend services and data handling
- Build and configuration are managed through .NET tools like Directory.Build.props and global.json
- Testing practices encompass unit and integration tests across the modular architecture
Code Quality
Jellyfin demonstrates a mature engineering approach with strong testing practices and consistent code conventions.
- Comprehensive test coverage and structured error handling ensure reliability across media operations
- Dependency injection is widely used to improve code maintainability and testability
- Code consistency and naming conventions support long-term readability and collaboration
- Some technical debt is present in duplicated logic and complex inheritance structures
What Makes It Unique
Jellyfin distinguishes itself through its commitment to privacy, extensibility, and open-source innovation in media server solutions.
- It provides a privacy-first alternative to proprietary media servers with no user tracking or data collection
- Extensive customization and plugin support enable users to tailor the experience for their specific needs
- Cross-platform compatibility ensures seamless operation across various devices and operating systems
- Unique metadata handling and naming conventions offer granular control over media organization