Expose a Current‑Time REST Endpoint in Node‑RED: A Step‑by‑Step Guide

Goal

Expose a REST endpoint that, when called with GET /time, returns a JSON object containing the current server time in ISO‑8601 format. The endpoint should be reachable at http://localhost:1880/time by default.

Prerequisites

• Node‑RED runtime installed and running locally on the default port 1880.
• Browser access to the Node‑RED editor (http://localhost:1880).
• Basic understanding of wiring nodes in Node‑RED.
• Optional: curl installed for command‑line testing.

Step 1: Add an HTTP In Node

1. Open the Node‑RED editor and drag an HTTP In node from the input palette onto the canvas.
2. Double‑click the node to configure it:
• Method: GET
• URL: /time
• Name (optional): GET /time
3. Click Done.

Step 2: Create a Function Node

1. Drag a Function node onto the canvas and wire it from the HTTP In node.
2. Double‑click the Function node and paste the following code into the editor:

msg.payload = {
    time: new Date().toISOString()
};
return msg;

3. Click Done.

Step 3: Wire to an HTTP Response Node

1. Drag an HTTP Response node onto the canvas and connect it to the Function node.
2. Leave the default settings (Status Code 200) and click Done.

Step 4: Deploy and Test

1. Click the Deploy button in the top right corner to activate the flow.
2. Open a browser tab and navigate to http://localhost:1880/time. You should see a JSON payload similar to:

{
    "time": "2026-09-16T12:34:56.789Z"
}

3. Alternatively, run the following command in a terminal:

curl -i http://localhost:1880/time

Expected output:

Status	Body
HTTP/1.1 200 OK	{"time":"2026-09-16T12:34:56.789Z"}

Troubleshooting & Recovery

• Endpoint returns 500 Internal Server Error:
  • Open the Node‑RED Debug panel and ensure the Function node’s output shows a valid object.
  • Verify that the Function node’s code ends with return msg; and that msg.payload is set.
  • Check that the HTTP Response node is wired from the Function node; a missing connection will cause a 500.
  • Review the console or node-red-log for stack traces.
• Port 1880 already in use:
  • Stop the existing service or change Node‑RED’s listening port by editing settings.js (e.g., uiPort: 1881).
  • Restart Node‑RED and redeploy the flow.
• Unexpected JSON format:
  • Ensure the Function node’s code uses msg.payload = { time: new Date().toISOString() }; and not a string.
  • Check that no other nodes modify msg.payload before the HTTP Response node.

Limitations & Best Practices

• Node‑RED is not intended for high‑performance, high‑concurrency APIs. For production workloads, consider a dedicated framework.
• Never expose sensitive data via this simple endpoint; sanitize any user input before including it in a payload.
• Keep the flow minimal; unnecessary nodes increase memory usage.
• Use the Node‑RED debug node sparingly in production to avoid large log files.
• Document the endpoint in your API reference for future maintainers.

Verification Checklist

• HTTP In node configured for GET /time.
• Function node returns an object with a time key.
• HTTP Response node connected and not overridden by another node.
• Deploy button clicked and flow status shows green.
• curl or browser returns 200 OK and valid JSON.
• Debug panel shows the payload object on each request.