Node, NGINX and MySQL can all be installed on Ubuntu via apt-get from the official repositories so they can certainly all run on one droplet.
While it will likely be possible to install this on a 512MB droplet, MySQL using it’s default configuration will likely exhaust the available memory and cause the service to crash at some point after you launch it. I would recommend a larger droplet or at least a swap file before you try and set this up.
This guide will walk you through installing Node.js
NGINX and MySQL can be installed by running
apt-get update
apt-get install nginx mysql-server

by Justin Ellingwood
One of the easiest way of increasing the responsiveness of your server and guarding against out of memory errors in your applications is to add some swap space. In this guide, we will cover how to add a swap file to an Ubuntu 16.04 server. <$>[warning] [label...