# cenkalti/rain

🌧 BitTorrent client and library in Go

Repository: https://github.com/cenkalti/rain
Canonical: https://ross.abutalabs.com/products/rain
Language: Go
License: MIT
License Family: permissive
Topics: torrent, bittorrent, p2p, golang
Last push: 2026-08-24T20:12:34+00:00

## Health v2 (maintenance only)
Score: 94/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 84, longevity 100
- inputs: {"age_days": 4487, "days_push": 9, "days_rel": 24, "gap_med": 59, "n_releases_24m": 10}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1144, forks 83 (observed 2026-08-28T04:03:45.069258+00:00)

## What it is
Rain is a high-performance BitTorrent client and embeddable Go library, running in production at put.io. It supports core BitTorrent BEPs including DHT, magnet links, UDP trackers, PEX, and encryption, with a client-server architecture exposing a JSON-RPC API and console UI.

## Use cases
- download torrents from magnet links in Go
- embed a BitTorrent client in my application
- create and parse .torrent files
- run a headless torrent server with RPC control
- stream downloads sequentially while downloading
- add torrent support to a self-hosted service

## When to choose
- you need a programmable BitTorrent client or library in Go
- you want a lightweight headless torrent daemon with JSON-RPC control
- you need DHT, magnet links, and tracker support without a GUI

## When to avoid
- you want a full-featured graphical torrent client like qBittorrent
- you need a torrent client in a language other than Go

## Facets
- artifact type: library
- maturity: active
- function: p2p, http-server, cli, serialization
- domain: networking, files, developer-tools
- platform: go, windows, cross-platform, cli
- tags: bittorrent, torrent-client, magnet-links, dht, -rpc, embeddable, linux, macos

## Member repositories
- cenkalti/rain (main) score 94

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:45.069258+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:34:44.062326+00:00, confidence not recorded.
  - readme: https://github.com/cenkalti/rain (fetched 2026-08-28T04:03:45.069258+00:00, sha c1102d61e635)
- Data as of 2026-08-30T08:39:29.467469+00:00.