HYDRA

A fast, resilient, multi-source file retriever and download engine.

Contents

• Overview
• Key Features
• Engine
• CLI
• Desktop GUI
• Installation
• Homebrew (macOS / Linux)
• Linux Packages (Ubuntu PPA / Fedora COPR)
• Quick Install (prebuilt binaries)
• From Source
• Browser Extension
• Uninstall
• Quick Uninstall (prebuilt installs)
• Usage
• Basic Download
• Multi-Connection & Mirror Sources
• CLI Compatibility (wget / curl Mode)
• Interactive Queue Manager (TUI)
• Remote Checksum Lookup & Verification
• Embedding HYDRA — libhydra
• Platform guides
• Contributing
• License

Overview

HYDRA is a high-performance network file retriever designed for speed, resilience, and adaptability. It dynamically partitions downloads across multiple connections and independent mirror sources, continuously rebalancing work to maximize throughput without stalling on slow peers. It ships as both a wget/curl-compatible CLI and a cross-platform desktop download manager with browser integration.

Key Features

Installation

Homebrew (macOS / Linux)

CLI:

brew install ja7ad/tap/hydra

macOS Desktop App (GUI):

brew install --cask ja7ad/tap/hydra

Linux Packages (Ubuntu PPA / Fedora COPR)

Ubuntu / Debian-based (Launchpad PPA):

sudo add-apt-repository ppa:sonycore/hydra
sudo apt update
sudo apt install hydra

PPA Repository: launchpad.net/~sonycore/+archive/ubuntu/hydra

Fedora / RHEL-based (Fedora COPR):

sudo dnf copr enable sonycore/hydra
sudo dnf install hydra

COPR Repository: copr.fedorainfracloud.org/coprs/sonycore/hydra

Quick Install (prebuilt binaries)

macOS / Linux — installs the GUI bundle (GUI + CLI + browser extensions) by default:

curl -fsSL https://raw.githubusercontent.com/ja7ad/hydra/main/install.sh | bash

CLI only:

curl -fsSL https://raw.githubusercontent.com/ja7ad/hydra/main/install.sh | bash -s -- --cli

Windows (PowerShell) — installs the GUI bundle by default:

irm https://raw.githubusercontent.com/ja7ad/hydra/main/install.ps1 | iex

CLI only:

& ([scriptblock]::Create((irm https://raw.githubusercontent.com/ja7ad/hydra/main/install.ps1))) -Cli

The scripts detect your OS and architecture (amd64/arm64), fetch the matching archive from the latest GitHub release, and install it — on Linux and macOS to /usr/local (falling back to ~/.local; override with --prefix DIR), on Windows to %LOCALAPPDATA%\Programs\Hydra. GUI installs also register the browser native-messaging host. Pin a release with --version vX.Y.Z / -Version vX.Y.Z, or download the archives yourself from the releases page.

A GUI install is a real desktop app, not a loose binary:

• Windows — a start-menu shortcut (-Desktop adds a desktop one) and an Apps & features entry, so Hydra is listed and uninstallable from Settings like any other app.
• macOS — Hydra Download Manager.app is installed into /Applications (override with --app-dir DIR, e.g. ~/Applications), with its icon and name in Launchpad, Spotlight, the Dock and the app switcher. hydra, hydra-gui and hydra-host in <prefix>/bin are symlinks into the app, so the CLI stays on PATH and one update refreshes both.
• Linux — the logo lands in the hicolor icon theme and a hydra.desktop entry in your applications directory (plus the prefix's, for a system-wide install), so the app shows up in the launcher, the dock and the switcher with its own icon.

Either way the GUI can update itself in place afterwards (Options → General → Check for updates), including an install that lives in a root-owned directory — it asks for authorisation before replacing those files.

Beta channel — --beta (-Beta on Windows) installs the newest -rc pre-release when it is ahead of the latest stable release; otherwise it installs the stable release:

curl -fsSL https://raw.githubusercontent.com/ja7ad/hydra/main/install.sh | bash -s -- --beta

& ([scriptblock]::Create((irm https://raw.githubusercontent.com/ja7ad/hydra/main/install.ps1))) -Beta

The GUI's in-app updater follows the same rule: enable Options → General → Download Beta channel and update checks will also offer release candidates while one is ahead of stable.

macOS notes: since the app isn't notarized yet, Gatekeeper may block it — see the macOS Permissions Guide for granting the required permissions. If you installed via the .dmg and macOS refuses to open the app ("damaged" or "unidentified developer"), clear the quarantine attribute:

xattr -cr /Applications/Hydra\ Download\ Manager.app

From Source

Ensure you have Rust (1.80+) installed:

git clone https://github.com/ja7ad/hydra.git
cd hydra
cargo build --release

The compiled binary will be located at target/release/hydra. To build the GUI and native-messaging host as well, run make build.

Browser Extension

Hydra integrates directly with web browsers to automatically capture downloads, provide right-click context menu options, and intercept media streams.

Official Store Listings (Recommended)

Install the extension directly from the official store for your browser:

• Chrome Web Store (for Google Chrome, Microsoft Edge, Brave, Vivaldi, Opera, Arc, and Chromium-based browsers):
  Chrome Web Store: Hydra Download Manager Integration
• Firefox Add-ons (AMO) (for Mozilla Firefox):
  Firefox Add-ons: HDM Integration
• Safari: Ships inside the macOS desktop application bundle (enable under Safari → Settings → Extensions).

Tip: In the desktop GUI, you can also view status and open extension store listings directly from Options → Extensions or the Extensions toolbar button.

Development & Manual Installation

Extension source code and resources are maintained under the extensions/ directory:

• extensions/chrome/ — Chromium MV3 extension source code (shared core).
• extensions/firefox/ — Firefox MV3 event-page add-on source.
• extensions/safari/ — Safari Web Extension resources.

Every installer also ships pre-built extension packages with the app in both packed (.zip / .xpi) and unpacked shapes:

Sideloading Unpacked / Development Builds

• Chrome, Edge, Opera, Brave, Vivaldi, Arc, Chromium — open chrome://extensions
  (edge://extensions, opera://extensions, …), turn on Developer mode, choose
  Load unpacked, and pick the extensions/chrome/ (or bundled chrome/) directory. The manifest key pins the id to
  jpnonmbbkjdpeebdhkjoliklfhkdcomj across all Chromium browsers, matching the native-messaging
  host allow-list. The packed .zip is the Web Store upload format, and the signed .crx is for enterprise policy
  deployment (ExtensionSettings / ExtensionInstallForcelist against an update manifest you
  host).
• Firefox — open about:debugging#/runtime/this-firefox → Load Temporary Add-on… and pick
  extensions/firefox/manifest.json or the packed .xpi. Developer Edition, Nightly, and ESR can install it
  permanently after setting xpinstall.signatures.required to false in about:config.

Building Extensions from Source

To build and assemble extensions from a repository checkout:

make extensions                                   # -> target/extensions
make extensions ARGS="--crx-key path/to/key.pem"  # also sign a .crx

A .crx is packed whenever a signing key is available (--crx-key, $HYDRA_CRX_KEY, or
target/hydra-chrome-crx.pem); --crx generates one if there is none. Sign with the key behind
the pinned manifest key — any other key changes the extension id, and the script says so.
ARGS=--sign additionally fetches an addons.mozilla.org-signed .xpi (needs web-ext and AMO
API keys).

Uninstall

Quick Uninstall (prebuilt installs)

macOS / Linux:

curl -fsSL https://raw.githubusercontent.com/ja7ad/hydra/main/uninstall.sh | bash

To also delete config, state, and logs:

curl -fsSL https://raw.githubusercontent.com/ja7ad/hydra/main/uninstall.sh | bash -s -- --purge

Windows (PowerShell):

irm https://raw.githubusercontent.com/ja7ad/hydra/main/uninstall.ps1 | iex

To also delete config and state:

& ([scriptblock]::Create((irm https://raw.githubusercontent.com/ja7ad/hydra/main/uninstall.ps1))) -Purge

Homebrew:

# Uninstall CLI
brew uninstall hydra

# Uninstall macOS Desktop App (and zap settings)
brew uninstall --cask --zap hydra

The scripts remove binaries, extensions, manifests, desktop shortcuts, and startup entries. On macOS, they also remove the bundled app and package receipts. Config and state are kept by default (~/.config/hydra on Linux/macOS, %APPDATA%\hydra on Windows); use --purge / -Purge to delete them.

Usage

Basic Download

# Retrieve a file with automatic concurrency discovery
hydra https://example.com/archive.tar.gz

# Specify output destination
hydra https://example.com/archive.tar.gz -o output.tar.gz

Multi-Connection & Mirror Sources

# Explicit connection count (e.g., 8 connections)
hydra -x 8 https://example.com/largefile.iso

# Fetch across multiple mirror origins serving identical files
hydra https://mirror1.example.org/file.iso https://mirror2.example.org/file.iso

CLI Compatibility (wget / curl Mode)

HYDRA can seamlessly emulate wget or curl flags:

# wget dialect
hydra --compat=wget -c -O myfile.zip https://example.com/file.zip

# curl dialect
hydra --compat=curl -C - -o myfile.zip https://example.com/file.zip

The dialect is also taken from the name the binary is invoked as, so existing
scripts can run unchanged. hydra compat-link installs those entry points:

# Show where the wget/curl links would go, and whether they would be reached
hydra compat-link --dry-run

# Create them next to the hydra binary
hydra compat-link

# Keep the real curl/wget names free
hydra compat-link --name hydra-wget --name hydra-curl

A link only takes effect from a directory that is on $PATH before the one
holding the real curl/wget — otherwise the shell keeps resolving the name to
the original tool. compat-link checks that and tells you which binary wins, so
a link that cannot be reached does not look like a silent failure. Existing files
are never replaced without --force.

Interactive Queue Manager (TUI)

# Launch interactive terminal UI
hydra interactive

# Add multiple downloads into the queue
hydra interactive https://example.com/file1.iso https://example.com/file2.zip

Remote Checksum Lookup & Verification

# Check remote advertised checksums without downloading the object
hydra checksum https://example.com/release.tar.gz

# Download with target hash verification
hydra --checksum sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 https://example.com/file.tar.gz

Embedding HYDRA — libhydra

hydra is the application. libhydra is the engine, and it is a product
in its own right: a stable C ABI over hya-core and hya-net, with its own
version, its own release archives, its own compatibility promise, and a
permissive MIT-or-Apache licence rather than the CLI's GPL. A desktop
application, an Android app, an iOS app, or a program in Go, Swift, Kotlin,
Dart, C# or Python can run the same download engine without taking the CLI or
the GUI with it.

make ffi          # libhydra.a, libhydra.so/.dylib, and include/hydra.h
make ffi-compat   # the ABI 1 stability gate
make ffi-test     # the ABI suite, a C conformance program, and every
                  # published header against the current library

#include "hydra.h"

hydra_engine_config_t cfg;
HYDRA_ENGINE_CONFIG_INIT(&cfg);
cfg.state_path = "hydra-state.json";     /* jobs survive a process restart */

hydra_engine_t *engine = hydra_engine_create(&cfg);

const char *urls[] = { "https://example.com/big.iso" };
hydra_job_config_t job;
HYDRA_JOB_CONFIG_INIT(&job);
job.urls = urls; job.url_count = 1; job.output_path = "big.iso";

hydra_job_id_t id;
hydra_job_create(engine, &job, &id);
hydra_job_start(engine, id);

Job identity is a durable uint64_t rather than a pointer, so it survives an
app restart, a UI rebuild or a killed Android service; the event queue is the
asynchronous interface, so it becomes a Go channel, a Kotlin Flow, a Swift
AsyncStream or a Dart Stream; and file bytes never cross the boundary, so
resident memory stays independent of object size.

The ABI is frozen and mechanically enforced. Within ABI 1 no field moves, no
enumerator is renumbered and no symbol disappears; CI checks the whole layout
against a committed manifest and compiles every header this project has ever
published against the library built from the current branch.
docs/ffi/ABI.md is the specification — design
principles, the stability policy, and what the guarantees actually cover.

Every release publishes a prebuilt archive — static library, shared library,
header, pkg-config metadata and these guides — for Linux (glibc and musl),
macOS, Windows, Android and iOS. Any other target builds from source with
scripts/build-ffi.sh --target <triple>, the same script CI runs.

Platform guides

See also docs/ffi/ABI.md for the specification,
include/hydra.h for the published declarations, and
examples/ffi-c/download.c for a complete C
client with mirrors, pause and resume.

Contributing

Contributions are welcome! Please read the Contributing Guide for the project layout, build instructions, pre-submit checks (fmt, clippy, tests), commit conventions, and how licensing applies to each crate. In short:

cargo fmt --all -- --check
cargo clippy --all-targets --all-features -- -D warnings
cargo test --all-targets --all-features

Bug reports and feature requests go to the issue tracker; security vulnerabilities should be reported privately via GitHub security advisories.

License

• The hydra CLI binary is licensed under the GNU General Public License v3.0 or later (GPL-3.0-or-later).
• The hydra-core, hya-net and hya-ffi libraries are dual-licensed under MIT or Apache-2.0 (LICENSE-MIT / LICENSE-APACHE).

For more details, see LICENSING.md and THIRD-PARTY-NOTICES.md.