Introduction In this article, I’m going to present you Lightrun, a very useful tool that I discovered recently while developing RevoGain, which helps me debug problems happening in production. Lightrun is like no other tool I’ve used before since it allows us to insert log entries dynamically at runtime, capture snapshots, and even inject metrics without changing your production code. This is especially useful when investigating issues reported by clients since we can figure out the problem while the user is executing the actions that can replicate the issue. Cool, right?