This tool is unofficial, and created hastily by Alvie (contact details can be found at https://alviemahmud.com).
Using this tool is quite simple (but can be finicky in instances). Input text in the boxes below, then hit "Create Poster". If the position of the subtext is off, play around with the Subtext Positioning settings, and micro-adjustment, then "Create Poster." Once you are happy with the preview, hit "Save Image" to download the image!