[dhh]

Here are some Rails sites: Basecamp, Github, Shopify, Airbnb, Soundcloud, Indiegogo. All have millions of users.

[mattangriffel]

Here's a list of about 35 popular Rails sites I've compiled: https://onemonth.com/ruby-on-rails-example-sites

[alco]

This list says little about Rails' productivity benefits without also stating how much is hidden behind it (in terms of queues, caches, async workers, etc.) to let those services handle their job.