Which http client of this app is usiing?

So I am following this whole tutorial to build my own side project but the difference is I am using Vue.js instead of React.js.
In this post https://serverless-stack.com/chapters/call-the-list-api.html, when I try to call the lambda function from the back end, it just use return API.get("notes", "/notes");and after searching in the code repo it seems like there is none http client is used.
I know that in Vue.js I can use Axios as the http client to make the request. But I want to use less module as possible to simplify my project. So can someone tell me how does this front end interact with aws lambda?

Many thanks in advance.

Internally AWS Amplify uses Axios but it does the authentication for us.