zerx-lab/FluxDown

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 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

{
  "mcpServers": {
    "fluxdown": {
      "url": "http://127.0.0.1:17800/mcp",
      "headers": { "Authorization": "Bearer " }
    }
  }
}

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.

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

# 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 apk --release       # or: ios

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

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.