LibreTorrent is an original Free as in Freedom torrent client for Android 4 and later, based on libtorrent. Download and share files directly on your device.

Source code:
gitlab.com/proninyaroslav/libretorrent

Implemented features:
- DHT, PeX, encryption, LSD, UPnP, NAT-PMP, µTP
- IP filtering (eMule dat and PeerGuardian)
- Ability to fine tune (network settings, power management, battery control, UI settings, etc.)
- Supports torrents with large number of files and big files
- HTTPS and magnet links support
- Support proxy for trackers and peers
- Ability to move files while downloading
- Ability to automatic movement of files to another directory or to an external drive at the end of download
- Ability to specify file and folder priorities
- Ability to select which files to download
- Ability to download sequentially
- Material Design
- Tablet optimized UI
- Scheduling
- RSS manager
- Android TV support
- Ability to create torrents
- Streaming of any selected files
- And more