mqspeak is MQTT client which collect data and transforms them into ThingSpeak channel updates or Phant data streams. It is able to handle multiple MQTT connections and independently update multiple channels.

It is written in Python3 and with use of paho MQTT library.

Application can be installed with following command:

$ sudo pip3 install mqspeak

Create systemd unit file /etc/systemd/system/mqspeak.service with following content:

[Unit]
Description=MQTT to ThingSpeak bridge
After=mosquitto.service

[Service]
Type=simple
ExecStart=/usr/local/bin/mqspeak -c /etc/mqspeak.conf -v
Restart=always

[Install]
WantedBy=multi-user.target

You can get source code of mqspeak at its GitHub page.