Fetch now supports making asynchronous requests.

You can now pass a callback function to fetch and fetch will pass the response to that callback function when it's received instead of blocking the rest of the code until it receives the response. Here's how you can do it:

// Fetch, in async mode, returns a FetchClient instead of returning the response.
FetchClient client;

void handleResponse(Response response) {
    Serial.println(response);
}

void setup() {
    // Setting options.
    RequestOptions options;
    options.method = "GET";

    // Making the request.
    client = fetch("http://api.grandeur.tech", options, handleResponse);

    Serial.println("This now prints before the response is printed.");
}

void loop() {
    // This is crucial, it listens on the connection for the response, until it's received.
    client.loop()
}

If you want to do more than one fetch, you need to create more than one FetchClient variables and more than one client.loop()s.

Only if you are doing fetch sequentially, that is, the next fetch happens after the previous fetch response has returned, then you can reuse the same FetchClient.