How to add or edit the value of an variable in a snippet of a template from the custom app installed

[GauthamSunny]

Hello,

Even if you know only small bit of the solution also please replay back. Everything is helpful.

I'm trying to build a custom app which communicates with an external API and saves the response from that API in a varaible of an snippet file.

So that I can render the data of the snippet variable to the store page and keep updating the snippet in the backend from by custom app.

I'm using node & react js.

Please help me out. 

Thanks in advance.

Gautham