Contract tests for two applications(not webservices) communicating by json file

I want to test communication between two applications(not webservices). One is generating json file as an output, second one is consuming this file. I would like to test if structure of this file is compatible with both applications. This file is stored in Azure. I was thinking about contract testing because they are faster then end-2-end tests, but in Pact's and Spring Cloud Contract's documantations I read that it is for REST communication tests. Could you help me find proper and fast way to test it?