Cannot GET /api/v1/ , MongoDb

Question

I am trying to test if my serving is working on post man. I tried pasting this http://localhost:80/api/v1/

and i got, Cannot GET /api/v1/

On my terminal on vs code, it looks like the server is running because it shows LISTENING TO PORT: 80 db connected.

here is my code

env file:

PORT=80
MONGO_URL =myurl

routes/transaction.js:

const express = require('express');
const router = express.Router();

router.get('/', (req, res) => {
  res.send('Hello, world!');
});

module.exports = router;

index.js:

const express = require('express')
const cors= require('cors')
const { db } = require('./db/db')
const {readdirSync} = require('fs')
const app = express()

require('dotenv').config()

const PORT =  process.env.PORT

//midwares
//data is in json
app.use(express.json())
app.use(cors())


//routes
readdirSync('./routes').map((route)=> app.use('/api/v1',require('./routes/' + route)))

const server = ()=>{
    db()
    app.listen(PORT,()=>{
        console.log('LISTENING TO PORT:',PORT);
    })
}

server()

I am using atlas, but I have also tried using mongoDB compass and i still get the same error