BitTorrent client and library in Go. Running in production at put.io.


  • Core protocol
  • Fast extension
  • Magnet links
  • Multiple trackers
  • UDP trackers
  • DHT
  • PEX
  • Message stream encryption
  • WebSeed
  • Fast resuming
  • IP blocklist
  • RPC server & client
  • Console UI
  • Tool for creating & reading .torrent files


If you are on MacOS you can install from brew:

brew tap cenkalti/rain
brew install rain

Otherwise, get the latest binary from releases page.


Rain is distributed as single binary file.
The main use case is running rain server command and operating the server with rain client <subcommand> commands.
Server consists of a BitTorrent client and a RPC server.
rain client is used to give commands to the server.
There is also rain client console command which opens up a text based UI that you can manage the torrents on the server.
Run rain help to see other commands.

Difference from other clients

Rain is the main BitTorrent client used at put.io.
It is designed to handle hundreds of torrents while using low system resources.
The main difference from other clients is that Rain uses a different port for each torrent.
This allows Rain to download same torrent from same private tracker for multiple users and keep reporting their ratio correctly.