What Web Server Does Node-Red Use?


Larry Thompson

When it comes to web servers, Node-RED relies on an underlying web server called Express. Express is a fast, unopinionated, and minimalist web framework for Node.js that provides a robust set of features for web and mobile applications. It is widely used in the Node.js community due to its simplicity and flexibility.

What is a Web Server?

A web server is a software application that handles incoming HTTP requests from clients (such as browsers) and delivers them the requested resources, typically HTML pages, images, or other static files. It also processes dynamic content by executing server-side scripts or interacting with databases.

Why does Node-RED need a Web Server?

Node-RED is a flow-based programming tool that allows users to create applications by connecting nodes together in a visual manner. It primarily runs on top of Node.js, which provides the necessary runtime environment for executing JavaScript code on the server-side.

However, Node.js alone does not have built-in capabilities to handle HTTP requests and serve web pages. Therefore, Node-RED relies on Express as its underlying web server to handle these tasks.

What makes Express a suitable choice for Node-RED?


  • The core philosophy of Express is simplicity. It provides just enough functionality out of the box without imposing any unnecessary restrictions or conventions.
  • This simplicity makes it easier for developers to understand and work with Express, especially when building custom features or integrating with other libraries.


  • Express offers great flexibility in terms of how routes are defined and how the request/response cycle is handled.
  • This allows developers to customize the behavior of the web server according to their specific requirements.


  • Express utilizes middleware, which are functions that can be used to modify the request and response objects before they are passed to the next middleware or the final route handler.
  • This feature enables developers to add additional functionality such as authentication, logging, or error handling to their Node-RED applications.

How is Express integrated into Node-RED?

Node-RED incorporates Express by utilizing a custom Express application instance. This instance is created and configured during the startup process of Node-RED and is responsible for handling incoming HTTP requests for accessing the Node-RED editor interface and REST API endpoints.

Within this Express application, Node-RED defines its own routes and middleware to handle specific functionality related to flow editing, user authentication, admin API access, and more. This integration allows Node-RED users to interact with their flows through a web browser or programmatically via REST API calls.


In conclusion, Node-RED relies on the Express web server as its underlying infrastructure for handling HTTP requests and serving web pages. The simplicity, flexibility, and middleware capabilities provided by Express make it a suitable choice for implementing the web server functionality needed by Node-RED. Understanding this underlying architecture can help developers extend and customize their Node-RED applications based on their specific requirements.

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