Json Schema file extension
From Gary Court:
I personally use .schema.json, but there is no official file extension. The official mime type however is "application/schema+json".
According to the last draft (v4), there is not a new extension proposed for files storing json-schemas. .json extension is used profusely within that document. .json is also the preferred extension in validators (PHP, Ruby, Python).
So I think that .json should be the preferred option in absence of an official/standard new extension.
I've started using .jschema after I had a run-in with an extension-based JSON Schema parser that automatically added id's to external RAML examples which are also .json files.
They are a specific format, after all. HTML is XML, which is UML, and we use a different file extension for each of those.