Set up an .env file with a MongoDB URI (at MongoDB).

You'll need to set up your own .env file on the main root folder that'll contain the MONGO_URI that is imported in the main server.js file as well as PORT=8000. The MONGO_URI variable in the .env file will look like this: MONGO_URI=mongodb+srv://<your_name>:<password>@<project_name>.xxxx.mongodb.net/<database_name>?retryWrites=true&w=majority.

You'll have to set up your own project at MongoDB. Just follow all the defaults.

Install needed packages

Install all the packages for both client and server folders with one command from the root folder with npm run setup

Then, from the root of the project, you can start the whole app, both the client and server folders, with one command in a terminal window: npm run dev. The server info will be in blue and the client info will be in green.

Now you'll see the project open up in your browser.

I deployed the backend to Heroku and the frontend to Github pages.

Here's the demo version: demo

Note: the web app will take a little bit to load when first going to the url. Same for when posting a new todo since I deployed the backend separately & is also affected by the platform's slow load due to free tier. This lag only last once, but afterwards the app performs at normal speeds.