Hi Sir,
I found your job and i think i would be great fit.
I have strong experience on Javascript, AJax with JSON. I'm also Java backend developer, so i understand when need to use Gson.
About Gson, this library helps you mapping JSON to Java object easily. You can also get JSON string from Java object by .toJson() function. But when i develop backend by Java, i prefer Jackson for mapping object because Jackson can also mapping XML type.
About Ajax: when you want to send HTTP request without reload a whole page, Ajax is best solution. However, when you use Ajax, your backend must allow Cross Origin (CORS).
About JSON: actually it is Javascript object. You can parse JSON object easily by Javascript.
That is my understanding about Gson, AJax and JSON.
I think my experience will meet your expectation.
I would like to talk with you further.
Best regards,
HungTV