I use Super Clean (used to be called Castrol Super Clean), Purple Power is another brand of basically the same stuff. Both are cleaner degreasers that you can find in auto parts stores. Just pour some in a container and let the parts soak, an hour or so will do a really good job, 15 minutes or so will take the chrome off but the undercoat takes more time. It doesn't hurt the plastic, I've forgotten parts and left them overnight without any problems.
Do not use it on resin parts, it will damage resin.
I've heard Westley's Blech White works too and this is safe for resin or plastic. It's a tire cleaner so again look for it at the auto parts store.
I know some people use oven cleaner, it works but its too stinky for me.
All of these will remove paint as well as chrome.