How to Host Express App on Vercel

Disclaimer: Vercel configuration file uses legacy builds and routes properties.

Last week I needed to host a simple Express app somewhere, and I decided to host it on Vercel because of the excellent Developer Experience.

Here are the steps that I needed to do to make it possible:

First, we need to create a project directory. I decided to name it vercel-express and then change the directory to a newly-created directory.

# create a directorymkdir vercel-express
# change directorycd vercel-express

Then we will initialize git and add the node_modules directory to .gitignore.

# initialize gitgit init
# add the `node_modules` directory to `.gitignore`echo node_modules >> .gitignore

Next, we need to set up a new package. We are using the -y flag to skip the questionnaire.

npm init -y

Then we will create an index.js file and populate it.

# create a new `index.js` filetouch index.js

// ./index.jsconst express = require('express')
const app = express()const port = 3000
app.get('/', (req, res) => {  res.send('Hello, Vercel!')})
app.listen(port, () => {  console.log(`Express app hosted on Vercel listening at port ${port}`)})

To run an express app, we need to create a custom vercel.json config file.

touch vercel.json

// ./vercel.json{  "version": 2,  "builds": [    {      "src": "./index.js",      "use": "@vercel/node"    }  ],  "routes": [    {      "src": "/(.*)",      "dest": "/"    }  ]}

After populating the index.js and vercel.json files, we can stage all of the files and commit them.

git add -A && git commit -m "Initial commit"

If you want to change the name for the main branch from master to main, simply run the git branch -m master main command.

For pushing code to the existing repository, follow the following code.

git remote add origin https://github.com/LukasPolak/vercel-express.gitgit branch -M maingit push -u origin main

The Vercel config file includes legacy properties, but it works like a charm when writing this. Maybe in the future, I will update the tutorial with the recommended properties.