Node-RED is a visual tool for flow-based programming that wires together hardware devices, APIs and online services. In a browser-based editor you drag nodes from a palette onto a workspace and connect them into flows. A flow is deployed to the runtime in a single click. Flows are stored as JSON, so they can be imported, exported and shared. The runtime is built on Node.js and runs both at the network edge on low-cost hardware such as a Raspberry Pi and in the cloud. You install Node-RED yourself, for example through npm.
Node-RED started in 2013 at IBM and is open source under the Apache-2.0 licence. The project is governed by the OpenJS Foundation, which holds the copyright together with other contributors. No vendor hosts your data: whoever runs Node-RED decides where the software and the data it processes reside. For a European organisation this means full control over hosting and updates, without dependence on a commercial cloud service, but also its own responsibility for operations and security.