I run Plunker (http://plnkr.co) that gets up to 20k daily active users. Users hammer the preview server[1] all day long generating a significant number of requests (by default it refreshes at each keystroke, debounced by 500ms or so).
That server runs happily as a single servo on http://modulus.io with absolutely no need for intervention on my part.
The rest of the application has similar requirements. I have one micro-equivalent server running the front-end, one the api and one the thumbnail generation. In general, this requires no hand-holding by me.
If your site is not processing or memory-intensive it should be feasible to scale to 10k users with a single $5/month instance on DigitalOcean or an equivalent level server on Heroku or Modulus or GCE.
That server runs happily as a single servo on http://modulus.io with absolutely no need for intervention on my part.
The rest of the application has similar requirements. I have one micro-equivalent server running the front-end, one the api and one the thumbnail generation. In general, this requires no hand-holding by me.
If your site is not processing or memory-intensive it should be feasible to scale to 10k users with a single $5/month instance on DigitalOcean or an equivalent level server on Heroku or Modulus or GCE.
Good luck attracting your first 5k users!
1: https://github.com/filearts/plunker_run/)