Transmission, a cross-platform, free, and open-source BitTorrent client, has just rolled out version 4.1. A major highlight of the new release is significantly improved µTP download performance, alongside broader networking enhancements.
The client now supports IPv6 and dual-stack UDP trackers, including compatibility with older BEP-7 trackers that rely on explicit &ipv4= and &ipv6= parameters. IPv6 Local Peer Discovery is also supported, while DHT performance has been refined to better handle modern network conditions.
Moreover, the release introduces a new JSON-RPC 2.0–compliant RPC API, modernizing Transmission’s remote control and automation capabilities. This update brings clearer version signaling, expanded statistics, new torrent state fields, and improved error reporting.
Transmission 4.1 also adds optional sequential downloading across clients, the daemon, and transmission-remote. This feature allows pieces to be downloaded in order and flushed to disk immediately after verification, enabling use cases such as media streaming during download. Additional controls allow sequential downloading from a specific piece, further improving flexibility for advanced workflows.
On the performance and efficiency side, libtransmission has been extensively optimized to reduce CPU usage, lower memory allocations, and decrease latency when communicating with peers. Disk I/O behavior has been refined to avoid unnecessary writes, better align throughput with transfer rates, and handle missing or temporarily unavailable data more gracefully.
Additionally, large torrents benefit from updated default piece sizes, while new settings provide finer control over caching, verification behavior, and TCP/µTP transport preferences.
On macOS, Transmission now improves dark mode support, modernizes system integration, updates Quick Look previews, and adopts newer APIs for power management and system sleep behavior. The Qt client gains better accessibility, visual refinements, label support from the web client, and improved handling of remote connections.
GTK users benefit from native file choosers, accessibility fixes, and stability improvements, while the web client sees substantial usability improvements, including drag-and-drop torrent uploads, improved filtering, responsive layout changes, and better accessibility and contrast handling.
Apart from the changes mentioned above, transmission-daemon gains more accurate logging, better systemd integration, support for sequential downloads, and improved configuration handling. transmission-remote adds idle seeding limits, enhanced statistics, clearer output formatting, and improved error reporting, making it more suitable for headless and server-side use.
Last but not least, Transmission 4.1 fixes a very large number of bugs, including crashes, protocol edge cases, tracker announce issues, locale and formatting errors, and regressions introduced in earlier 4.x releases.
For more information, see the changelog.
