TrickleBar

TrickleBar is a menu app based on aria2 that provides a minimal interface to view and manage your downloads. It requires aria2 to be installed and available in $PATH or other common locations, but you can also override which aria2 binary to use. It has a minimal settings panel to configure aria2 options.

tricklebar menu app screenshot tricklebar settings panel screenshot
abdusco tricklebar A lightweight macOS menu bar download manager, backed by aria2c. Swift 1 0

It also provides a CLI that allows you to add new downloads, and passes the extra switches to aria2c.

> TrickleBar.app/Contents/MacOS/TrickleBar --help
tricklebar — aria2c-compatible download manager

Usage:
  tricklebar [options] URL...     Add download(s) to running daemon
  tricklebar -i FILE              Read URLs from file
  open TrickleBar.app             Launch menu bar interface

Options (subset of aria2c flags):
  -d, --dir=DIR                Download directory
  -o, --out=FILE               Output filename
  -s, --split=N                Connections per download
  -x, --max-connection-per-server=N
  ...
  -h, --help
  -v, --version

It listens to tricklebar:// URLs to add downloads. You can even specify which script to run when a download is done. I use it to automatically move the downloaded file to the right folder and show a notification, for example.

url="$1"
encoded=$(python3 -c "import urllib.parse, sys; print(urllib.parse.quote(sys.argv[1]))" "$url")
open "tricklebar://add-download?on_done=$HOME/bin/aria2_on_done.py&url=$encoded"

You can download the latest version from GitHub.