I was actually following these steps: const form = new FormData() form.append('image_file', photo) form.append('mask_file', mask) fetch('https://clipdrop-api.co/cleanup/v1', { method: 'POST', headers: { 'x-api-key': YOUR_API_KEY, }, body: form, }) .then(response => response.arrayBuffer()) .then(buffer => { // buffer here is a binary representation of the returned image }) but since i'm a complete newbie on js(i'm a statistician, know some r, some python, but had never touched js) i'm struggling as hell think it might be a good idea to get some 2 days of a js intro course to get to know the place kkkk