First release of NanoTorrent based on PicoTorrent.

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NanoTorrent

NanoTorrent is a tiny, hackable BitTorrent client for Windows — a Rust 2024
port of PicoTorrent. It keeps the
original's application structure, settings database and behaviour while
replacing the C++ / Rasterbar-libtorrent / wxWidgets stack with pure-Rust
building blocks.

Site: https://www.nanotorrent.org

This port is built predominantly with AI assistance under human review — see
AI-DECLARATION.md.

On first run NanoTorrent does a one-time copy of an existing
%LOCALAPPDATA%\PicoTorrent data folder (settings + session state) into
%LOCALAPPDATA%\NanoTorrent, leaving the original untouched.

Building

Requires Rust 1.85+ (edition 2024) and the MSVC toolchain Rust already uses on
Windows. No C++ dependencies.

cargo build --release

The binary is target/release/nanotorrent.exe. Ship the lang/ folder next to
it for translations (falls back to the embedded en-US otherwise).

The engine is vendored: vendor/librqbit (and vendor/librqbit-tracker-comms)
are the published crates.io sources plus a small stack of mostly
visibility-only patches, wired in via [patch.crates-io]. See
vendor/librqbit/PATCHES.md; build.rs verifies the patches are present and
fails with instructions if a re-vendor dropped one. Re-vendor with
tools/update-librqbit.ps1.

What's included

• Session — DHT (persisted routing table), UDP trackers, listen port,
  -NT- Azureus-style (or random, in anonymous mode) peer id, up/down rate
  limits, SOCKS proxy with per-scope toggles (peers / trackers / hostnames),
  fast-resume across restarts. Settings are applied live — Preferences ▸ OK
  rebuilds the session, no restart needed.
• MSE / PE encryption — both outgoing and incoming, RC4, require-encryption
  toggles (src/bittorrent/mse.rs, injected through a vendored transform seam).
• libtorrent tuning knobs — every setting PicoTorrent exposed that can
  function against librqbit: active-download/seed/overall limits, pause on low
  disk space, PeX toggle, anonymous mode, proxy scoping. Ones with no librqbit
  mechanism are documented as no-ops.
• Settings database — the exact original migration SQL (incl. the custom
  get_known_folder_path() / get_user_default_ui_language() SQLite
  functions); a pre-existing PicoTorrent DB migrates cleanly.
• Main window — torrent list with all 16 columns, a rendered progress
  bar in the Progress column, click-to-sort, multi-select, context menu
  (pause/resume, remove with/without files, force recheck, move storage,
  labels, copy info hash / magnet, open in Explorer). Paused torrents blank
  their live columns.
• Details tabs — Overview (with a piece-availability bar), Files (per-file
  include toggles), Peers (with GeoIP country), and Trackers grouped into
  announce tiers with per-tracker seeds/leeches/fails/next-announce plus
  DHT/LSD/PeX source rows.
• Add flows — Add torrent (parsed file list, save path, label, start
  toggle); Add magnet, which fetches the metadata first and then shows the
  same dialog with the real file list.
• Torrent creation — BitTorrent v1, v2 and hybrid (BEP 52), with tracker /
  comment / private options.
• Notifications — real Windows 11 toasts on download-complete, under a
  registered AppUserModelID; a notification-area (tray) icon with close-to-tray
  prompt.
• File associations — register NanoTorrent for .torrent files and
  magnet: links from Preferences.
• GeoIP & IP filter — DB-IP country lookup for peers; eMule/PeerGuardian
  blocklists.
• Import — one-shot import of every torrent from an existing PicoTorrent
  database (File ▸ Import from PicoTorrent).
• Filters — the PQL query subset (status = "downloading" and dl > 1kbps),
  plus an optional console input.
• Labels — colors, save paths, per-torrent assignment, filtering,
  auto-apply.
• Single-instance — a second launch forwards its command line (torrent
  files / magnet links) to the running instance and exits.
• Translations — all original language files, selectable in Preferences;
  the UI text is localized with an embedded en-US fallback.
• Crash log — a panic hook writes a backtrace to the logs folder (the
  original used Crashpad; there is no upload).

Known differences / not yet ported

• uTP peer transport is deferred — there is no production-ready async Rust
  uTP crate. UDP trackers and DHT work; only µTP peer connections are missing.
• LSD does not exist in librqbit, and it does not attribute peer counts to
  a discovery source, so the DHT/LSD/PeX tracker rows are status-only (no
  seeds/leeches numbers there).
• A few libtorrent.* advanced settings are stored but have no librqbit
  equivalent to apply (documented as dead).
• Windows will not let an app force-set the magnet protocol default when
  another client registered it system-wide (anti-hijacking); the associations
  button registers NanoTorrent and opens Settings ▸ Default apps so you can
  confirm it.
• The update checker retains the original's endpoint, which may be defunct.