Sherm nailed it. Originally it was called Castrol Super Clean and used as an engine degreaser.
It might only be called Super Clean, or Purple Clean depending on your area, but you can get it at any auto parts store or possible Home Depot or Walmart if your area has it. The stuff is technically non-toxic, biodegradeable, no fumes etc, but you need to use gloves because it'll suck the moisture out of your hands in seconds in a very uncomfortable way. For stubborn old paint, it may take overnight or longer, but doesn't harm plastic and you can reuse it over and over again. I've left full models in in for weeks on end with no issues.
It's amazing. I've been using to strip 50 year old enamel off of old Aurora kits to restore, but also used in to take chrome off some auto bumpers, etc.
For chrome it works in minutes, you just fill a jar, drop 'em in, go back a short while later pull out squeaky clean white styrene, pour it back into the jug.
The stuff truly lives up to the hype.