https://www.thethingsnetwork.org/docs/applications/nodered/quick-start.html
As an aside: it seems your node is sending plain text, even JSON? That’s a waste of bandwidth. (Is that an example from badgerboard.io?) If you ever change that to send a few bytes instead, then note that decoding can also be done in TTN’s payload functions, so any MQTT client will get ready-to-use data (including Node-RED).