Mystique is an MQTT server that implements most parts of the MQTT v3.1.1 specification.
In Docker:
docker pull thethingsindustries/mystique-server
docker run -d -p 1883:1883 thethingsindustries/mystique-server
Install and run from source:
go get github.com/TheThingsIndustries/mystique/cmd/mystique-server
mystique-server --help
Permissions: ✅ Commercial use, ✅ Modification, ✅ Distribution, ✅ Private use
Limitations: ❌ Liability, ❌ Warranty
Conditions: ℹ License and copyright notice