Discourse http://www.discourse.org
Mini Profiler https://github.com/miniprofiler/rack-mini-profiler
rbtrace https://github.com/tmm1/rbtrace
memory_profiler https://github.com/SamSaffron/memory_profiler
fast_stack: https://github.com/SamSaffron/fast_stack