You can parse the JSON and then immediately re-serialize the parsed object:

var myJson = `{
    "name": "sample name",
    "product": "sample product",
    "address": "sample address" 
}`;

// 'Minifying' the JSON string is most easily achieved using the built-in
// functions in the JSON namespace:
var minified = JSON.stringify(JSON.parse(myJson));

console.log(minified);

You'll have to perform the minification server-side to get an improvement in response size. I suppose most languages support an equivalent to the above snippet. For example, in php one might write this (if your server runs php, of course):

$myJson = '{
    "name": "sample name",
    "product": "sample product",
    "address": "sample address" 
}';

$minified = json_encode(json_decode($myJson));