Error while fetching JSON with JavaScript

So I’m new to JSON fetching here, and currently implementing a JSON API in my current project. My code works fine when using a direct .json-file link, but when trying to fetch from the live link (ending with my API key and the parameters, rather than the file extension) it shows nothing. The log shows that the JSON fetching was successful but it obviously doesn’t get any data.

Here is my current code:

fetch('https://api.dropinblog.com/v1/json/?b=XXXXXXXXXXXXXXXXXX&limit=2')
            .then(function (response) {
                return response.json();
            })
            .then(function (data) {
                appendData(data);
                console.log('Success!');
            })
            .catch(function (err) {
                console.log('error: ' + err);
                alert('Error: ' + err);
            });
        function appendData(data) {
            var mainContainer = document.getElementById("myData");
            for (var i = 0; i < data.length; i++) {
                var div = document.createElement("div");
                div.innerHTML = "Status: " + data[0].status + "<br />" + "ID: " + data[0].data["posts"][i].id + "<br /><br />" + "<img src=" + data[0].data["posts"][i].featuredImage.split('"').join('') + "><br /><br />" + data[0].data["posts"][i].title;
                mainContainer.appendChild(div);
            }
        }

As you can see I am still just playing around with the code and trying to figure out how to fetch the data. I would like to keep it Vanilla JS as much as possible!

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Also – I am using a CORS-anywhere addon in Chrome at the moment -, I am aware that I am going to need a proxy or similar for fetching later, when it’s uploaded to the host. I have been looking around a lot for the best ways to do this and even setup a localhost proxy the other day but could not get it to work. Is there any easy and simple workaround for the CORS-problem?