There's a long list on <a href="https://github.com/ekremkaraca/awesome-rails" rel="nofollow">https://github.com/ekremkaraca/awesome-rails</a>, the most "grown up" app might be <a href="https://github.com/gitlabhq/gitlabhq" rel="nofollow">https://github.com/gitlabhq/gitlabhq</a><p><a href="https://rubyweekly.com/" rel="nofollow">https://rubyweekly.com/</a> collects advanced articles, conference summaries, new tools. I prefer it over blogs or individual tutorials.