black-hole is a configurable XMPP ↔ Discord bridge written in Python 3.6.

It uses Discord.py@rewrite and aioxmpp.

Worth reading through just because it demonstrates how to use aioxmpp.

websocketd is a small command-line tool that will wrap an existing command-line interface program, and allow it to be accessed via a WebSocket.

WebSocket-capable applications can now be built very easily. As long as you can write an executable program that reads STDIN and writes to STDOUT, you can build a WebSocket server. Do it in Python, Ruby, Perl, Bash, .NET, C, Go, PHP, Java, Clojure, Scala, Groovy, Expect, Awk, VBScript, Haskell, Lua, R, whatever! No networking libraries necessary.

A universal bridge for communications protocols. Presents a unified REST API so you don't have to worry about writing your own protocol adapters.

Protocols: IRC, XMPP, Gitter, Mattermost, Slack, Discord, Telegram, Rocket.Chat, Hipchat (via XMPP), Matrix, Steam, ssh-chat and Zulip

Appears that it's "one instance of this bridge to one service at a time."