I am building an App based on Node.js running on Heroku.
The app uses a JSON file which at the moment is being pushed with the rest of the app, and we are reading and wr
Disclosure: I am the node.js platform owner at Heroku.
You will need to bring the state out of your application. For replacing JSON files in a node app, you should look at mongo, s3, and redis:
Personally, I prefer redis for simple use cases (it sounds like yours might qualify). You can just dump JSON in and parse it out. Alternatively, the most popular redis client for node provides a friendly interface for simple hashes:
https://github.com/mranney/node_redis#friendlier-hash-commands
Redis, mongo, s3: