Byebug is a simple to use, feature rich debugger for Ruby 2. It uses the
new TracePoint API for execution control and the new Debug Inspector API
for call stack navigation, so it doesn't depend on internal core sources.
It's developed as a C extension, so it's fast. And it has a full test
suite so it's reliable.

WWW: https://github.com/deivid-rodriguez/byebug