If you’ve got static content, Github Pages is convenient and pretty easy to use. (There are NPM packages that will automate the deploy process – try searching for gh pages deploy).
If you need server-side processing with the language of your choice, the only free solution I know of is Heroku (edit:) and Zeit (but they’re limited). For paid solutions, Zeit’s Now, Heroku, and Digital Ocean are all great. I believe Ellie uses Zeit’s Now.