FluxDown

Downloads, Supercharged.

A blazing fast, multi-protocol download manager — the free & open-source IDM alternative.

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Highlights

Up to 10x faster — Rust + Tokio engine with IDM-style dynamic segmentation
Multi-protocol — HTTP/HTTPS, FTP, BitTorrent, eD2K, HLS & DASH streaming
Browser integration — Chrome / Edge / Firefox extension with a 3-layer interception engine
AI-agent ready — built-in MCP (Model Context Protocol) server: let Claude, Cursor & other AI clients manage your downloads
Resume anywhere — full download state persisted in SQLite; survive crashes and reboots
Beautiful UI — light/dark themes, 13 color schemes, responsive three-pane layout
Clean & private — free and open source, no ads, no tracking, no account required, local-first

Features

Feature	Description
Rust-Powered Engine	Built on Rust and Tokio with zero-cost abstractions — memory-safe concurrency at maximum throughput
Smart Segmentation	Segments split dynamically at runtime; idle threads rescue slow segments, just like IDM — but smarter
Multi-Protocol	Dedicated engines for HTTP/HTTPS, FTP, BitTorrent (DHT/UPnP/magnet), eD2K (server + Kad DHT source finding, MD4 verification), HLS (AES-decrypt) and DASH
Speed Control	Token-bucket global rate limiting — download in the background without killing your browsing
Resume Anywhere	Every byte tracked in SQLite with WAL; power loss never costs you progress
Browser Integration	Three-layer download interception, streaming media sniffing, Alt+Click bypass, right-click send
MCP Server	Built-in Model Context Protocol endpoint (Streamable HTTP) with 12 tools — AI agents can add, monitor and control downloads
Beautiful Interface	shadcn-style widgets, IDM-style segment visualization, named queues, system tray
Clean & Private	Zero ads, zero telemetry lock-in, zero accounts — your data never leaves your machine

FluxDown vs. IDM

	FluxDown	IDM
Price	Free & open source	$24.95 + renewals
Open source	Yes (AGPL-3.0)	No
Platforms	Windows / macOS / Linux / NAS / Android	Windows only
BitTorrent & magnet	Yes	No
eD2K / eMule links	Yes	No
HLS / DASH streaming	Yes	Partial
Dynamic segmentation	Yes	Yes
Browser extension	Chrome / Edge / Firefox	Yes
Ads & tracking	None	—

Installation

Grab the latest build from GitHub Releases or fluxdown.zerx.dev:

Platform	Packages
Windows (x64 / ARM64)	`setup.exe` installer · portable `.zip`
macOS (Intel / Apple Silicon)	`.dmg` · portable `.tar.gz`
Linux (x64)	`.AppImage` · `.deb` · Arch `.pkg.tar.zst` · portable `.tar.gz`
Android (arm64-v8a / armeabi-v7a / x86_64)	per-ABI `.apk` · universal `.apk`
NAS / Server (headless, x64 / ARM64)	Docker · Synology DSM 6/7 `.spk` · QNAP `.qpkg` · OpenWrt `.ipk` · Unraid CA template · CasaOS / ZimaOS app store

Browser Extension

Install the extension so FluxDown takes over browser downloads automatically:

MCP Server (Model Context Protocol)

FluxDown ships a built-in MCP server so AI agents (Claude Desktop, Cursor, Cline, …) can manage downloads via the Model Context Protocol. It speaks Streamable HTTP (JSON-RPC 2.0 over a single POST /mcp) on the local API port — no extra process needed.

Endpoint: http://127.0.0.1:17800/mcp (local-only by default)
Auth: Bearer token (Authorization: Bearer <token> or X-FluxDown-Token), shared with the management API
Enable: Settings → API Service → toggle MCP endpoint (a token is generated automatically); the headless server enables it by default

Tools (12)

Tool	Description
`download_add`	Create a download task (HTTP/HTTPS, FTP, magnet, BitTorrent)
`download_list`	List tasks with progress/speed/status, optional status filter
`download_get`	Get a single task by ID
`download_pause` / `download_resume`	Pause / resume one task
`download_pause_all` / `download_resume_all`	Pause / resume all tasks
`download_remove`	Remove a task, optionally deleting downloaded files
`queue_list`	List named queues and their configuration
`rss_list`	List RSS subscriptions with their configuration and runtime state
`rss_add`	Subscribe to an RSS feed and start polling it on a schedule
`rss_remove`	Delete an RSS subscription and the items it collected

Client configuration

config.json

{
  "mcpServers": {
    "fluxdown": {
      "url": "http://127.0.0.1:17800/mcp",
      "headers": { "Authorization": "Bearer <your-token>" }
    }
  }
}

The MCP layer is implemented in native/api/src/mcp.rs on top of the same ApiHost trait that powers the REST management API and aria2-compatible JSON-RPC.

Architecture

Flutter renders the UI; a zero-FFI Rust engine does the heavy lifting. The two talk through Rinf signals, and the browser extension connects via Native Messaging.

mermaid

flowchart TD
    EXT["Browser Extension (WXT)"] -->|Native Messaging| NMH["fluxdown_nmh"]
    NMH -->|Named Pipe / Unix socket| HUB
    UI["Flutter UI (shadcn_ui)"] <-->|Rinf signals| HUB["hub — FFI adapter"]
    HUB --> ENGINE["fluxdown_engine"]
    ENGINE --> HTTP["HTTP/HTTPS"]
    ENGINE --> FTP["FTP"]
    ENGINE --> BT["BitTorrent"]
    ENGINE --> ED2K["eD2K"]
    ENGINE --> HLS["HLS / DASH"]
    ENGINE --> DB[("SQLite")]

Layer	Tech	Path
UI	Flutter + shadcn_ui	`lib/`
FFI bridge	Rinf (Dart ↔ Rust signals)	`native/hub/`
Download engine	Rust + Tokio (zero FFI deps)	`native/engine/`
Browser extension	WXT + TypeScript	`fluxDown/`
Website	Astro + React	`website/`

Building from Source

Prerequisites: Flutter SDK · Rust toolchain · Rinf CLI

shell

# Clone the development branch (main = active development, stable = stable releases)
git clone -b main https://github.com/zerx-lab/FluxDown.git
cd FluxDown

# Check your environment
rustc --version
flutter doctor

# Install the Rinf CLI (once)
cargo install rinf_cli

# Fetch dependencies & generate Dart bindings
flutter pub get
rinf gen

# Run in debug mode
flutter run

# Build a release
flutter build windows --release   # or: macos / linux

Linux system dependencies

shell

# Debian/Ubuntu
sudo apt-get install cmake ninja-build clang pkg-config \
  libgtk-3-dev libayatana-appindicator3-dev libnotify-dev libsecret-1-dev patchelf zstd

# Arch Linux
sudo pacman -S cmake ninja clang pkgconf gtk3 libayatana-appindicator libnotify libsecret patchelf zstd

The NMH relay binary (fluxdown_nmh) is built automatically by CMake during flutter build. Distribution packages (AppImage / deb / Arch / portable) are produced by CI on every tag.

Running tests

shell

flutter test                          # Dart tests
cargo test -p fluxdown_engine        # Rust engine tests
cargo test -p hub                    # FFI adapter tests

Contributing & Community

Bug reports / feature requests — GitHub Issues or the in-app feedback dialog
QQ Group — 832143651

Pull requests are welcome! Branch off main and target main — it is the development branch, while stable only tracks stable releases (maintainers advance it from main). Before submitting, please make sure:

shell

cargo fmt --check && cargo clippy -- -D warnings   # Rust
flutter analyze                                     # Dart

See CONTRIBUTING.md for the full workflow.

License

Distributed under the GNU Affero General Public License v3.0.

If FluxDown saves you time, consider giving it a Star — it helps more people discover the project.

Made by zerx-lab