Skyshark is a python decoder for ACARS messages, roughly inspired by wireshark. It parses JSON output from acarsdec and attempts to guess the meaning of received messages. Where possible, it will disambiguate messages types with multiple interpretations using other metadata, such as aircraft registration or flight ID.
Along with some of the message decoders, there is some tooling that uses MongoDB as its backing store for aircraft registration (not every country is as nice as the US about publishing downloadable databases), as well as ADSB observations from dump1090