Old question I hear you think But still it will get asked when you start Ruby on Rails projects for clients. One way of comforting a client is just naming a few RoR success stories: “Twitter uses Rails, it has about 8.000.000 unique visitors a month.”.

Evan Weaver has a nice comparison of some big Rails sites on his blog. Together with some nice graphics. It shows Rails can scale.. and it also shows that’s not the only question. See his blog for more nice graphs.

So you see.. there are quite some site that have pretty much requests (vertical bar = # of requests). For example: twitter.com, yellowpages.com, etc..