Something is calling POST /inform in nodejs express project - node.js

Question

I have a pretty simple nodejs project that uses express. When I start this project locally I have noticed that something is calling a POST to /inform about every 30 seconds. I'd like to know what's calling inform and what the purpose is.
I'm new to node. Is this normal? I haven't implemented a route for this call so it causes a 404.
Here's my main app:
const createError = require('http-errors');
const express = require('express');
const path = require('path');
const cookieParser = require('cookie-parser');
const logger = require('morgan');
const fileUpload = require('express-fileupload');
const app = express();
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use(fileUpload());
// routes
const indexRouter = require('./routes/index');
const usersRouter = require('./routes/users');
app.use('/', indexRouter);
app.use('/users', usersRouter);
// catch 404 and forward to error handler
app.use((req, res, next) => {
console.log(req)
next(createError(404));
});
// error handler
app.use((err, req, res) => {
// set locals, only providing error in development
res.locals.message = err.message;
res.locals.error = req.app.get('env') === 'development' ? err : {};
// render the error page
res.status(err.status || 500);
res.render('error');
});
// Start the server
const PORT = process.env.PORT || 8080;
app.listen(PORT, () => {
console.log(`App listening on port ${PORT}`);
console.log('Press Ctrl+C to quit.');
});
In my console, I see this about every 30 seconds:
POST /inform 404 14.002 ms - 2158
POST /inform 404 13.910 ms - 2158
POST /inform 404 31.536 ms - 2158
EDIT:
Thank you for the comments. I changed my express port to 8000 and it no longer happens. So something on my local machine is looping and posting to localhost:8080/inform. I'll have to trace this down.

Answer 1

I have a Ubiquity Unify network stack at home. After running (and stopping) the Unifi Controller on my laptop, all my Unify devices continue to send a POST <laptop IP>:8080/inform.
My own application was getting its logged filled up with the same unknown route: "/inform" error.
Solutions:
Choose a different port
Bind your application to 'localhost' instead of '0.0.0.0'
Get a dedicated controller device, like a Raspberry Pi or Unifi Cloud Key

Answer 2

This could be pretty much any application on your PC or even other systems in your local network, if you are listening on public addresses.
You could implement the route to see if the request header/body give any hint as to where this is coming from.
It may also be possible for external software such as Wireshark to monitor network calls to localhost, including their source.
Otherwise use a different port where no one is sending periodic pings to.