Torch Browser vs aria2

Torch supports sequential downloading that allows users to download files in sequential order. That means that media such as video or audio can be streamed a the same way it can be with any other streaming service.

Torch is a Chromium-based web browser designed for heavy consumers of social media. It includes a features such as a media grabber that is capable of downloading videos from video sharing sites such as YouTube or Vimeo, a built-in player that's capable of streaming media while it's still downloading and of course a download manager that's capable of handling torrents. And since it has the same backbone as Google's Chrome, Opera, Safari or Vivaldi browsers it safe to say that it's reliable and fast. It's also compatible with all Chrome add-ons.

Built-in search engine allows finding torrents to download right from withing the torrent client.

Due to aria2 being a CLI only tool it uses very little memory.

Has support for lots of download protocols including BitTorrent, Metalink, HTTP, HTTPS and FTP.

XML or JSON-based RPCs can be used to control aria2 remotely with both APIs completely documented. Simplest client that uploads torrent to be downloaded is 3 Python lines long (no 3rd-party libraries, only stdlib).
Run aria2c --help=#rpc to see more.

Some web interfaces consist of pure HTML+JS, no server-side needed (except aria2c of course). It uses the same RPC that can work even over WebSockets.