Often when discussing OSGi at events, conferences or forums, we hear things like, “Yeah, I like JRebel but now we are using OSGi”, or “Does JRebel support OSGi”, or “Isn’t OSGi the same as JRebel?”. Sometimes it happens that people start comparing OSGi to JRebel, which is kind of like comparing a Ferrari to a Skyscaper; thus, this article is designed to a) explain the differences on a technical level what JRebel and OSGi do, b) outline some ideal use cases for OSGi and JRebel c) clear up any grey areas or misconceptions between the two technologies. So, let’s go!