There are 4 repositories under matrix-appservice topic.
An open source integration manager for matrix clients, like Element.
Wechaty [Matrix] Application Services Bridge
A Matrix-Google Chat puppeting bridge
A Matrix-Twilio relaybot bridge.
Matrix Application Service framework in Go
[WIP] E is a multi-purpose and multi-protocol command & control server designed to receive commands through the Matrix chat protocol and forward them to clients.