MJTC — MJ Torrent Client

MJTC is a high-performance BitTorrent client for Windows built around an in-house torrent engine and a dense, real-time monitoring interface.

Rather than hiding protocol activity behind a single progress bar, MJTC exposes torrent, peer, piece, transport, verification, DHT, GeoIP, and transfer state directly in the UI.

Performance · Visibility · Control

Download

Download the latest stable binary from Releases:

MJTC-v1-win-x64.exe

MJTC v1 is published as a self-contained, single-file Windows x64 executable. A separate .NET runtime installation is not required.

Each stable release also includes SHA256SUMS.txt so the downloaded executable can be verified before running it.

Get-FileHash .\MJTC-v1-win-x64.exe -Algorithm SHA256

Compare the result with the value in SHA256SUMS.txt from the same release.

Highlights

Custom BitTorrent engine developed specifically for MJTC
.torrent and magnet-link support
BitTorrent v1, v2, and hybrid torrent support
TCP and µTP operating concurrently
DHT, Peer Exchange, Local Peer Discovery, and HTTP/UDP trackers
Web-seed engine support (included in v1, not yet surfaced as a desktop feature)
Protocol Encryption / Message Stream Encryption support
High-throughput piece scheduling and endgame handling
Selective file downloading and file-level priorities
Built-in torrent verification and force-check workflows
Detailed torrent, peer, and file progress visualization
Live piece maps and temporary purple new-progress overlays
Rich peer telemetry with client/version identification
Configurable Peer ID profiles using recognized client signatures
Integrated GeoIP city/country lookup and vector country/subdivision flags
Global and per-torrent bandwidth controls
Persistent torrent/session state and historical transfer statistics
Transfer graphs and configurable refresh cadence
System-tray integration and fast restore
Optimized single-file distribution with embedded runtime assets

Getting Started

System requirements

Operating system: Windows x64
Runtime: Included in the executable
Framework target: .NET 10 / WPF
Network: Internet access and permission through the local firewall

MJTC stores its application state under:

%LOCALAPPDATA%\MJTC

The application organizes persistent data into subdirectories for state, network identity, statistics, logs, cache, lists, downloads, and other runtime data.

Installation

MJTC is portable and does not require a traditional installer.

Download MJTC-v1-win-x64.exe from the latest GitHub release.
Optionally verify its SHA-256 checksum against SHA256SUMS.txt.
Place the executable wherever you want to keep it.
Start MJTC.
If Windows Firewall asks for network permission, allow the network access appropriate for your environment.

If Windows displays a reputation or publisher warning, review the executable and release checksum before proceeding. Windows warnings do not by themselves indicate that the downloaded file differs from the release asset.

Adding Torrents

Open a `.torrent` file

Open MJTC.
Use the torrent-add control or open a .torrent file associated with MJTC.
Choose the destination and file selection as required.
Start the torrent.

MJTC parses the torrent metadata, initializes the selected files, restores reusable local data when applicable, and begins peer discovery through the mechanisms permitted by that torrent.

Add a magnet link

Copy a magnet URI.
Open Add Magnet in MJTC.
Paste the magnet and confirm.
MJTC begins peer discovery and metadata acquisition.

Magnet support includes metadata exchange and file-selection parameters where supplied by the URI.

Torrent Management

MJTC supports the normal torrent lifecycle together with lower-level controls not normally exposed by simple downloaders.

Common actions

Start
Pause
Resume
Remove torrent
Remove torrent and optionally remove payload data
Force-check / verify local data
Select or deselect individual files
Change file priority
Apply torrent-specific bandwidth limits
Apply torrent-specific connection limits
Inspect torrent details and piece state
Export/copy torrent and magnet information where available

Paused torrents are removed from active transfer scheduling rather than merely being visually marked as paused.

Custom BitTorrent Engine

MJTC does not wrap a third-party torrent engine. The application contains its own BitTorrent implementation, including:

Bencoding parsing and writing
Torrent metainfo parsing
Peer handshakes and peer-wire messages
Choking / unchoking
Piece and block requests
Piece scheduling
Piece verification
Upload scheduling
Endgame behavior
Tracker communication
DHT
Peer Exchange
Local Peer Discovery
Web seeds (engine implementation included; not yet surfaced in the v1 desktop workflow)
Magnet metadata acquisition
TCP transport
µTP transport
Protocol encryption / obfuscation
NAT traversal / hole punching
Torrent persistence and resume state

Keeping the engine inside MJTC allows networking and scheduling behavior to be tuned together with the application's UI telemetry and persistence model.

Peer Discovery

MJTC can discover peers through multiple independent sources:

HTTP trackers
HTTPS trackers
UDP trackers
DHT
Peer Exchange (ut_pex)
Local Peer Discovery when enabled
Magnet-provided peers
Hole-punch/rendezvous paths when negotiated and applicable

Private torrents are treated specially: discovery mechanisms that must not be used for private swarms are disabled for those torrents.

TCP + µTP

MJTC supports TCP and µTP concurrently.

The transport controls are designed to influence the proportion of connections without unnecessarily starving one transport. The engine can replenish connections from trackers, DHT, and PEX as peer availability changes.

µTP implements the BitTorrent µTP transport, including SACK handling and congestion/retransmission behavior.

Protocol Encryption / Obfuscation

MJTC supports BitTorrent Message Stream Encryption / Protocol Encryption (MSE/PE) for peer connections.

Modes can permit, require, or refuse encrypted peer handshakes depending on configuration.

MSE/PE should be understood as protocol obfuscation and compatibility functionality, not as end-to-end anonymity or a replacement for transport security/privacy tools.

Piece Scheduling and Endgame

The transfer engine contains an availability-aware piece and block scheduler with support for:

Per-peer request windows
Adaptive request pipelines
Request timeout recovery
Pipeline refill
Duplicate-request protection
Unique-block-first behavior
Stale-request recovery
Selective-download awareness
Endgame scheduling
Bounded rescue duplicates
Cancellation of unnecessary duplicate requests

Near completion, MJTC attempts to keep healthy peer pipelines productive without turning endgame into uncontrolled duplicate-request traffic.

Torrent Verification and Data Integrity

MJTC verifies torrent payload against the hashes defined by the torrent format rather than assuming that bytes present on disk are valid.

Verification support includes:

Piece hash verification
File-aware force checking
Per-piece verification state
Verification progress visualization
Recovery after files are deleted or externally modified
Synchronization between verification and active downloading
Resume-state integration
v1 SHA-1 piece verification
v2 Merkle/SHA-256 verification
Merkle torrent verification where applicable

If previously downloaded files are manually removed, MJTC can re-evaluate local piece ownership and download the missing data again.

Files and Selective Downloads

The Files view exposes per-file state inside each torrent.

Depending on the torrent format and state, MJTC tracks:

File path
File size
Selection state
Priority
Completion
Piece distribution
Verification state
Newly downloaded progress

Magnet file-index selection is supported when provided by the magnet URI.

Progress Visualization

MJTC uses detailed progress visualization across the Torrents, Peers, and Files views.

The UI can represent:

Overall completion
Piece ownership
Selected-file completion
Missing pieces
Active transfer state
Availability
Verification state
Newly acquired data

State colors

Green — active/downloading state
Teal — completed / fully available state
Purple — newly received progress
Gray — paused / inactive state
Red — blocked or error-related state where applicable
Orange — warning/intermediate state where applicable

New progress is temporarily highlighted with a purple overlay so recent acquisition can be distinguished from older completed data.

Detailed Peer Monitoring

MJTC exposes live and historical information for peers, including:

IP address
Port
Country flag
Client identity
Client version
TCP / µTP transport
Encryption state where available
Download rate
Upload rate
Downloaded amount
Uploaded amount
Piece availability
Completion percentage
Connection state
Blocked state
First seen / last seen information
Session information
Geographic information

Disconnected, blocked, and previously observed peers can remain visible according to the application's history/retention behavior instead of disappearing immediately.

Peer ID and Client Identification

MJTC implements BEP 20 peer-ID recognition and maintains a broad catalog of known client signatures.

Recognized families include, among others:

qBittorrent
µTorrent
BitTorrent
Transmission
BiglyBT / Vuze / Azureus
Tixati
MonoTorrent
libtorrent
libTorrent (Rakshasa)
BitWombat
Folx
Xunlei
Free Download Manager
WebTorrent
LibreTorrent
PicoTorrent
Gopeed
aria2
many additional historical and current BitTorrent implementations

The Peer ID & Port control can generate a fresh 20-byte Peer ID using registered client profiles and their version/signature conventions. Unknown or opaque peer IDs are not force-mapped to a known client and may be displayed as randomized/unavailable instead.

GeoIP and Flags

MJTC integrates geographic peer information directly into the peer interface.

Features include:

Country detection
City lookup when available
Country/subdivision flag rendering
Peer-detail geographic information
Embedded GeoIP payload
Indexed vector flag resource pack

The runtime does not require a loose GeoIP database or a directory full of SVG files beside the executable.

GeoLite attribution

This product includes GeoLite Data created by MaxMind, available from MaxMind.

DHT

MJTC contains an integrated BitTorrent DHT implementation with IPv4/IPv6-aware behavior.

The engine includes support for routing-table maintenance, bootstrap, peer discovery, external-address evidence, DHT security extensions, read-only behavior, mutable/immutable items, and other DHT extensions listed in the BEP table below.

The UI exposes DHT state such as running status, buckets, and known nodes.

Trackers

Tracker support includes:

HTTP/HTTPS announce
UDP announce
Compact peer lists
IPv4 and IPv6 peers
Multi-tracker tiers
Tracker scrape
UDP tracker extensions
DNS tracker preference handling
Retry metadata where provided

Web-seed engine support

_{MJTC v1 includes BEP 17/BEP 19 web-seed parsing and transfer code in the engine, but web seeds are not yet surfaced as a normal desktop feature/control. They are therefore treated as an engine-only capability in the BEP table below rather than an advertised v1 workflow.}

Bandwidth and Connection Controls

MJTC provides both global and per-torrent controls.

These include:

Global download limit
Global upload limit
Per-torrent download limit
Per-torrent upload limit
Per-torrent connection limits
TCP / µTP preference
Connection replenishment behavior
Encryption policy
DHT/PEX/LSD-related controls
Advanced networking limits

Persistent State

MJTC keeps torrent/session state across application restarts.

Persisted data can include:

Torrent metadata/repository data
Piece completion
File selection
Running/paused state
Resume data
Peer-related history where applicable
Verification state
Network identity/port settings
Historical statistics
UI/window state

Performance-sensitive state uses compact binary formats where appropriate, with legacy migration paths retained where needed.

Statistics and Graphs

MJTC maintains session and historical statistics, including:

Torrents downloaded
Data downloaded
Data uploaded
Sharing percentage
DHT status
DHT buckets
DHT nodes

The Sharing value is expressed as a percentage and is not capped at 100%.

Sharing = Uploaded / Downloaded × 100

MJTC also provides global and per-torrent transfer graphs. Per-torrent graph history can continue accumulating while a different torrent is selected.

Streaming

The engine contains file-streaming support for consuming selected torrent files while data is being acquired, subject to piece availability and the torrent/file state.

Streaming-aware scheduling can prioritize the pieces needed by the active stream without disabling normal torrent integrity checks.

System Tray and Desktop Integration

MJTC includes Windows desktop integration such as:

System-tray operation
Fast hide/restore behavior
Window-state persistence
.torrent/magnet startup argument handling
Single-instance forwarding
Custom multi-resolution application icon

BitTorrent Enhancement Proposal (BEP) Support

MJTC v1 contains a broad set of BitTorrent protocol implementations. The table distinguishes between capabilities used by the current application and code that is present in the engine but is not yet surfaced by the v1 desktop workflow.

Status legend

Active — used by normal MJTC v1 operation or directly exposed by the application.
Automatic — used internally when the protocol/torrent requires it; no dedicated control is necessary.
— implementation is included in the binary but is not yet used/surfaced as a normal MJTC v1 desktop feature. These rows are intentionally visually muted.

BEP	Feature	MJTC v1 scope	Status
3	BitTorrent Protocol Specification	Core peer-wire protocol, metainfo, trackers, piece transfer	Active
5	DHT Protocol	DHT node, peer discovery, PORT messages	Active
6	Fast Extension	Have All/None, Reject, Suggest, Allowed Fast	Automatic
7	IPv6 Tracker Extension	IPv6 HTTP/UDP tracker announce and peer parsing	Automatic
9	Extension for Peers to Send Metadata Files	Magnet metadata acquisition (`ut_metadata`)	Active
10	Extension Protocol	Extended handshake and negotiated extension IDs	Automatic
11	Peer Exchange (PEX)	`ut_pex` receive/broadcast with private-torrent restrictions	Active
12	Multitracker Metadata Extension	Tracker tiers / multi-tracker operation	Active
13	Protocol Encryption	MSE/PE peer protocol obfuscation support	Active
14	Local Service Discovery	Local Peer Discovery, configurable	Active
15	UDP Tracker Protocol	UDP announce/scrape support	Active
16	Superseeding	Initial/super-seed mode and Fast-extension integration	Active
₁₇	_{HTTP Seeding (Hoffman-style)}	_{Web-seed parsing/transfer implementation is present, but web seeds are not yet surfaced as a normal v1 desktop workflow.}
₁₉	_{HTTP/FTP Seeding (GetRight-style)}	_{Web-seed parsing/transfer implementation is present, but web seeds are not yet surfaced as a normal v1 desktop workflow.}
20	Peer ID Conventions	Client decoding and configurable peer-ID profiles	Active
21	Extension for Partial Seeds	Upload-only/partial-seed signaling	Automatic
23	Tracker Returns Compact Peer Lists	Compact peer response parsing	Automatic
24	Tracker Returns External IP	External-address evidence used by tracker/network identity paths	Automatic
27	Private Torrents	Disables DHT/PEX/LSD/hole-punch paths as required	Automatic
29	µTorrent Transport Protocol	µTP transport, SACK and retransmission/congestion logic	Active
30	Merkle Hash Torrent Extension	Merkle torrent parsing, proof/hash-piece transport and verification	Automatic
31	Tracker Failure Retry Extension	Tracker retry directives and backoff handling	Automatic
32	IPv6 Extension for DHT	IPv6 DHT operation	Automatic
₃₃	_{DHT Scrape}	_{Scrape request/response and Bloom-filter code is present, but the current v1 application does not initiate the DHT scrape workflow.}
34	DNS Tracker Preferences	DNS tracker preference resolution	Automatic
35	Torrent Signing	Signature metadata parsing and verification	Automatic
₃₆	_{Torrent RSS Feeds}	_{Feed parser/service code is included, but the v1 desktop application does not expose feed subscriptions or auto-add controls.}
38	Finding Local Data Via Torrent File Hints	Authenticated local payload reuse/hint handling during add/restore	Automatic
39	Updating Torrents Via Feed URL	Update URL monitoring and successor-torrent handling	Automatic
40	Canonical Peer Priority	Canonical peer-priority calculation	Automatic
41	UDP Tracker Protocol Extensions	UDP tracker extension support	Automatic
42	DHT Security Extension	Secure DHT node-ID/address handling	Automatic
₄₃	_{Read-only DHT Nodes}	_{Read-only DHT mode exists in engine configuration, but it is not currently surfaced by the v1 desktop application.}
44	Storing Arbitrary Data in the DHT	Immutable/mutable DHT item support; also underpins mutable-torrent functionality	Automatic
45	Multiple-address Operation for the BitTorrent DHT	Multi-address / IPv4+IPv6 DHT behavior	Automatic
46	Updating Torrents Via DHT Mutable Items	Mutable-torrent magnet resolution, subscriptions and update handling	Active
47	Padding Files and Extended File Attributes	Padding, symlink/attribute metadata and file-layout handling	Automatic
48	Tracker Protocol Extension: Scrape	Extended tracker scrape handling	Automatic
₄₉	_{Distributed Torrent Feeds}	_{Metadata parsing, validation and builder/feed primitives are included, but distributed-feed operation is not yet surfaced in the v1 desktop workflow.}
₅₀	_{Publish/Subscribe Protocol}	_{DHT topic publish/subscribe service and protocol handling are included, but the v1 desktop application does not expose topic subscription/publishing.}
₅₁	_{DHT Infohash Indexing}	_{sample_infohashes responder/sampling infrastructure is included, but no normal v1 desktop workflow initiates or exposes infohash sampling.}
52	BitTorrent Protocol Specification v2	v2/hybrid metainfo, SHA-256 Merkle trees, hash exchange	Active
53	Magnet URI Extension — Select Specific File Indices	`so=` file-index/range selection	Active
54	`lt_donthave` Extension	Piece-withdrawal send/receive semantics	Automatic
55	Holepunch Extension	`ut_holepunch` rendezvous/connect/error handling	Automatic

Official BitTorrent Enhancement Proposal index: bittorrent.org/beps

Security and Privacy

MJTC does not require an account or a hosted MJTC service to operate. Application state is stored locally on the Windows machine.

BitTorrent itself is a peer-to-peer protocol. When participating in a swarm, your network address can be visible to peers, trackers, DHT nodes, web seeds, and other infrastructure involved in that torrent. MJTC is not an anonymity tool.

Protocol Encryption / MSE can obfuscate BitTorrent traffic but does not make peer-to-peer activity anonymous.

Use MJTC only for data you are legally authorized to download, distribute, or share.

Troubleshooting

MJTC does not start

Verify that you downloaded the executable from the repository's official Releases page.
Verify the SHA-256 checksum.
Check whether Windows Security or another endpoint-security product quarantined the file.
Review %LOCALAPPDATA%\MJTC\Logs\crash.log if a crash log was generated.

Downloads are slow

Check the torrent's seed/peer availability.
Check global and per-torrent bandwidth limits.
Check the per-torrent connection limit.
Verify that Windows Firewall permits MJTC's network traffic.
Check tracker and DHT state.
Review whether TCP/µTP preferences or encryption settings are overly restrictive.

Magnet metadata does not arrive

Confirm that the magnet has a valid info hash.
Ensure DHT/trackers are available for that torrent.
Wait for a peer supporting metadata exchange.
Private torrents depend on their permitted tracker/peer-discovery paths.

A completed torrent becomes incomplete

If payload files were removed or modified outside MJTC, run a force check. The client will re-evaluate the local data and reacquire missing pieces as needed.

Firewall/NAT problems

Allow MJTC through Windows Firewall as appropriate. NAT traversal, UPnP/NAT-PMP, and peer hole punching can help where supported, but successful incoming connectivity still depends on the router, ISP, firewall, and remote peer.

Support and Bug Reports

Use the repository's Issues section for reproducible defects and feature requests.

For bug reports, include as much of the following as possible:

MJTC version (for example v1)
Windows version/build
Whether the torrent was .torrent or magnet-based
Torrent type when known: v1, v2, hybrid, private, web-seeded, etc.
Exact steps to reproduce the issue
Expected behavior
Actual behavior
Relevant screenshots
Relevant MJTC settings
Relevant crash/log information from %LOCALAPPDATA%\MJTC\Logs

Do not post private tracker passkeys, authentication tokens, personal paths, or other secrets in public issues.

For performance reports, also include approximate torrent size, piece count, peer count, connection limit, TCP/µTP preference, and observed transfer rate.

Release and Versioning Policy

Public MJTC versions use compact version labels without redundant zero components:

v1
v1.1
v1.1.1
v1.1.2
v1.2
v2

Pre-release labels may use a descriptive suffix, for example:

v1-beta

The release asset follows the same public version:

MJTC-v1-win-x64.exe
MJTC-v1.1-win-x64.exe
MJTC-v1.1.1-win-x64.exe

Distribution

MJTC is currently distributed as a compiled Windows binary. Application source code is not included with the binary release.

The executable is self-contained and carries the runtime resources needed by the application, including optimized embedded assets used by the UI, GeoIP, and flag system.

Legal Notice

MJTC is provided for legitimate peer-to-peer file transfer. Users are responsible for ensuring that they have permission to download and distribute the content they use with the application.

Third-party data and technologies remain subject to their respective terms and licenses.

This product includes GeoLite Data created by MaxMind, available from https://www.maxmind.com/.

Project Direction

MJTC is designed as both a practical torrent client and an observable BitTorrent implementation.

Development priorities include:

Throughput · Protocol Correctness · Reliability · Persistence · UI Accuracy · Large-Swarm Performance · Transfer Integrity · Observability

Name		Name	Last commit message	Last commit date
.github/ISSUE_TEMPLATE		.github/ISSUE_TEMPLATE
.gitattributes		.gitattributes
.gitignore		.gitignore
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
SECURITY.md		SECURITY.md

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