EXTERNAL - data.json decode

How can I implement an site wide read only external JSON file by key. In other words I will have several pages populated from the json file based on the key: (Id: 1) all information associated on that page. (Id: 2) that information on the next page. Etc.

I saw the json decode filter in grav however I don't know how to implement it.

Any help would be greatly appreciated.

A documentation update is pending approval. You can see the section on working with external files here.

Thank you. I'll give it a good read.

merged!