ShareX has custom uploader support and you can easily import/export these.
If you need help while making custom uploader you can check here:
But easiest way to learn is checking other example custom uploaders to see how those work.
Please use current custom uploader naming format for consistency; name and file name should be just domain with lowercase:
If one domain has more than one service or profile then add that info near it with paranthesis:
example.com (Image uploader).sxcu example.com (URL shortener).sxcu
example.com (Anonymous).sxcu example.com (User).sxcu