Mailchimp webhook to retrieve new subscriber data to json file

Hi. What I need is a simple php code. I want to create a webhook for my audience on mailchimp with url to that php code. Every time there is a new subscribe in my mailchimp audience I want it to “push” it to that php code where I can for example export it to json file. By default I want add each subscribe to my MySQL db but it would enough if some could provide me a code that will display data in json. I think I’ll modify it. Anyway. I hope it’s quite understandable. I can pay max 15 bucks for this task. It’s a small task.