[coupdejarnac]

I haven't seen it mentioned yet, but Redhat's Openshift provides an alternative to Heroku. I've used it for a few years and been happy with it. They have a startup program that gives you access to a paid tier for a year. I've used Openshift to host Node and Flask apps.

Edit: a bunch of downvotes for trying to be helpful, how nice.

[LaurentVB]

I was pretty happy with openshift until I recently discovered it was impossible to update the version of an os package I depended on. On heroku, custom buildpack and it was done in 5 minutes.